The yield and quality of black medick seeds(Medicago lupulina L.) produced from different fertilization and flowering position was investigated was investigated to develop the technology of seed vigor maintenance. Number of flowers and seeds, 100 seeds weight, yellow seed percentage, and large seed percentage were higher in seeds produced from stems than in those from branches. Increase of nitrogen resulted in a higher rate of yellow and large seeds as well as 160 seeds weight. Germination rate was the highest (56.9%) in the yellow seeds harvested from stems which were grown with a treatment of lower level of nitrogen and higher level of phosphorus. Malformed seedlings were frequently observed among the seedlings grown from seeds which were produced only with phosphorus.