Abstract: Apple leaf blotch is a serious disease in Kunming, and it h asexually induced by Marssonina coronaria. The sexual generation of the fungus is Diplocarport mali. After two years' observations on ovcrwinlcring characteristics of the it is found that, the fungus overwinters in diseased leaves in two forms, proloapothccium find hypha mass wilh ascogone in it. The former develops into matured apothccium when temperature rises next year and releases ascospores from May to July, The later becomes a special form of accrvulus and the ascogone without fertilization branched, and finally becomes two-cell conidiospore which is different in morphology from the conidiosporo fortneH in growth season.