本文应用余弦模型对河南省流脑季节性特征进行了分析。结果表明，流脑菌苗接种后，流脑发病率已降至较低水平，流行期明显延长，为１～５月份，病例呈更趋分散状态。但季节性发病高峰无明显变化，仍在３月份，提示目前流脑菌苗接种应在１２月上旬以前完成，同时还对余弦模型在分析疾病高峰期差别中的显著性检验方法进行了探讨 In this paper, the seasonal characteristics of meningitis in Henan Province are analyzed by cosine model. The results showed that after the vaccination of meningococcal vaccine, the incidence of meningitis has dropped to a lower level, the epidemic was significantly prolonged, for the 1-5 months, the case was more dispersed state. However, there was no significant change in the peak seasonal incidence, which is still in March. It indicates that current meningococcal vaccine inoculation should be completed before the end of December. At the same time, the significance test of cosine model in analyzing the difference of peak period of disease was also discussed