多数传染病的发病存在季节性 ,研究疾病的季节性规律有利于探索致病因素、预测流行时间、实施防治措施。本文运用向量合成表示法 -集中度和圆形分布对南京市 1987年～ 1997年 8种法定传染病的季节分布特点进行了分析。1　资料与方法1.1　资料来源 :　南京市卫生防疫站历年疫情 The seasonal distribution of the most infectious diseases exists. It is helpful to study the seasonal patterns of the disease, explore the causative factors, predict the prevalence of the epidemic, and implement the prevention and treatment measures. This paper analyzes the seasonal distribution of eight notifiable infectious diseases in Nanjing City from 1987 to 1997 by using vector composite notation - concentration and circular distribution. 1 Materials and Methods 1.1 Source: Nanjing Epidemic Prevention Station epidemic over the years