〔Abstract〕 Objective To investigate the effect of humidex on traffic injury. Methods A Poisson generalized linear regression combined with distributed lag non-linear model was applied to analyze the relationship between humidex and the incidence of traffic injury. Stratified analysis was carried out according to gender and age. Results The relationship between traffic injury and humidex is nonlinear. The risk effect increased first and then decreased with the increase of humidity, but the overall risk effect was statistically significant. The adverse effect of humidex(25 percentile of humidex) was the largest on the day of exposure(P25:RR=1.102(1.010～1.201)), and ended in 5-days lag. Subgroup analysis indicated that male and the population who aged>14-<65 were affected by humidex at lag 0-5 days. Conclusion Humidex can significantly increase the risk of traffic injury, and has the lagged effects.