There are more positive effects of the horticultural therapy group on the elderly. To understand the group therapeutic factors is to contribute to decide and modify group strategies and concepts, and promote abilities of group practices. The purpose of this study was to explore the therapeutic factors of empowerment-based horticultural therapy group on the elderly. The horticultural therapy group was designed by the concepts of the empowerment in combination with horticultural activities. There were eight sessions in this group program, including understanding plants, planting plants, gardening and horticultural activities. The group was led by a horticultural therapist and a certified counselor. There’re 10 over the age of 65 older people who lived in urban areas invited to participate this group. The research methods were used quantitative and qualitative mixed design. The data collection was conducted using quantitative questionnaires and qualitative interviews. ""Group therapeutic factor inventory"" were conducted after second, fifth, and last session of this group, and semi-structed in-depth interviews were conducted after the end of the group to understand the therapeutic factors for elderly people participated in this group. The statistical results of questionnaire surveys were found that was a high frequency of ""positive feeling for group"", ""action elicitation"" and ""cognitive acquisition"" in the early stage, ""positive feeling for group"" and ""action elicitation"" in the medium-term stage, while ""positive feeling for group"", ""action elicitation"" and ""altruism"" in the latter stage of the group. Overall, the highest frequency of ""positive feeling for group"" occurred. In order to understand the frequency differences of group therapeutic factors between stages, the Nonparametric statistics method were utilized. The significant differences between the stages were found. There were early and medium-term stage, medium-term and the latter stage of the group, but no difference between early and the latter stage of the group. It had been observed that each frequency of the eight group therapeutic factors has significantly promoted in the latter stage of this group. The results of the interview data analysis were that six beneficial factors such as ""sharing works, accomplishments, horticultural skills learning, expectations, positive emotions, and health concerns"" have positive contributions to the elderly. ""Sharing works"" were referred to the psychological sharing derived from the completion of horticultural products, that is, the horticultural therapy process allowed the elderly to have the opportunity to share the works completed in the process, and could benefit positively through sharing. ""Accomplishments"" were referred to the sense of accomplishment of participating in the horticultural activities. The elderly people felt the gains and achievements through the participation process of this group. ""Horticultural skills learning"" were referred to the learning of gardening related skills, that is, the elderly experienced the cooperation, exchange and learning of related skills through the participation of the group. ""Expectations"" were referred to expect to participate this horticultural therapy activities, that is, the elderly expressed their expectations and hope for the continuation and participation of future groups in the process of participating in horticultural therapy group. ""Positive emotions"" meant the process of horticultural activities brings positive emotions and relief effects, that is, the elderly generally experienced positive relief effects through the participation of horticultural activities, and also have a positive effect on the catharsis of emotions. ""Health concerns"" meant that the elderly participants discussed health issues between and after this group sessions, that is, who were involved in this horticultural therapy group to, and experienced the importance of physical health issues through the group process. Overall, there were positive benefits for the elderly participated in the empowerment-oriented horticultural therapy group. Understanding the connotation of group therapeutic factors under the context of horticultural therapy has reference value for the construction and implementation of horticultural therapy for the elderly. According to the research results, it was suggested that a therapeutic factor scale with horticultural therapy characteristics can be developed in the future, and relevant recommendations were provided for follow-up studies and practices.