To determine an optimum harvest time for Chinese milk vetch (CMV) seed production, the seeds were harvested at 4 times, according to 25, 30, 35, and 40 day after flowering (DAF), in Mir yang, southern part of Korea. CMV plants were manually harvested at each time and seed threshing was done by rice threshing machine. Seed yield, 1,000-seed weight, germ inability, and hard coat ratio were investigated. Seed yield was the highest, 53.9 kg/300 kg by dry weight (DW) of CMV plant, at 35 DAF. 1,000-seed weight increased according to seed harvest time from 25 DAF to 40 DAF when it was 3.10 g. The germination ratios of seeds harvested at 4 times were not significantly different when the seeds stored until August 1. In case of long period of CMV seeds stored, the seeds harvested later showed higher germination rate. On the other hand, because the hard coat ratio causing germination inhibition was declined with an increase of storage period, it was higher in the seeds harvested later. There was no difference among the seeds harvested at 4 times at October 1. In conclusion, it was presumed that an optimum harvest time for CMV seed production should be at 35 DAF considering seed yield, weight and germ inability.