Abstract: Spore germination and protonema development of Pylaisiella polyantha (Hedw.) Grout in response to Knop and distilled water. The medium of these two condition is agar. The spores of Pylaisiella polyantha is well developed, its protonemata and gametophyte are formed. The process from the spore germination and protonema growth to development of the gametophyte are illustrated and taken microphotographs. The result shows that the time of spore germination at two condition is 53.5 hours, the germination pole is 1-4 poles.There is a contrast to germination rate of the two groups. After 4 days, the germination rate of experiment group is 85.4%, the other is 54.1%. About the 20th day bud primordium appears. Nearly 40th day, the gametophyte fully grow and starts development of sexual organs. Besides, the characteristic about (development) of the gametophyte are analysed and discussed in this paper.