Abstract: The development of Kjellmaniella crassifolia Miyabe gametophytes were tested under different illumination and photoperiod under laboratory conditions. The results indicated that the illumination and photoperiod had significant effects on the development rate of K.crassifolia Miyabe gametophytes (P<0.05). The results indicated that: 1) The optimum condition for the development of gametophytes was 20~40 μmol·m-2s-1 under the condition of different light intensity. The development rate was about 60%~80% and the reproductive growth was significantly faster than that of other groups. 2) Under the conditions of different photoperiod, the growth rate was 6.68%~69.87% under the condition of 20L∶ 4D at the 12th~25th day of culture. The development rate was not significantly different from that of the 16L∶8D experimental group, but significantly higher than that of other groups. The development rate (74.54%) was the highest and the number of sporozoite cells was the most in the treatment group of 20L∶4D. This research could provide reference information and data for the amplification cultivation and seedlings of K. crassifolia Miyabe gametophytes.