Abstract: This paper dealed with the initial infection source and physiological character of Phoma asparagi Sacc.The investigation showed that the main sources of initial infection come from the diseased stem residues and plants of asparagus which overwintered in field.The pathogen could survive in the diseased stems on soil surface and 15 cm underground for 300 and 30 days respectively.The germination rate of pycnidiospores was determined under 5-25℃ on PSA medium.It germinated in all temperature treatments after 24 hrs, only germinated in 10℃ and 15℃ treatments after 48 hrs, and all failed to germinate after 72 hrs.The optimum relative moisture and temperature for producing pycnidia were 95%-100%and 20-30℃.respectively.on PSA medium, the optimum temperature,pH and carbon source for mycelial growth were 20-30℃, pH 7-8 and glycerin respectively.