The purpose of this study was to examine the effect of horticulture occupation therapy program via healing garden which is increasing the emotional stability and hand Dexterity enhancement on pre-vocational rehabilitation of chronic mental disorder. The current study included 29 patients who were diagnosed as chronic mental disorder under the rehabilitation service at E capital hospital in Seoul from February to December 2010. All of patients participated with agreement in this study, then were divided randomly by experimental (n=17) and control groups (n=12). Therapeutic program was consisted with total 38 sessions, and performed once a week for 10 months. Experimental group was treated with horticultural occupational therapy program using a healing garden (one time), as well as general occupational therapy (four times) in a week. Control group was conducted only general occupational therapy five times a week. To evaluate the effects of program, physical and psychological stress test and hand dexterity test was used before and after program. The program was based on the person-centered therapy, then paired t-test was used to compare the results before and after the program. In the results of present study, there were no significant differences of psychological and physical stress between before and after the therapy in experimental and control group, respectively. However, hand dexterity of experimental group was markedly changed between before (112..4±50.9 sec) and after (82.1±40.6 sec) therapy. Moreover, the speed of performance in GPT was increased with rising therapeutic sessions, indicating the hand dexterity was improved after program. These results demonstrated that horticultural occupation therapy program using the healing garden is beneficial for pre-vocational rehabilitation of chronic mental disorder.