Objective To find the relationship between preschoolers' temperament and asthma occurrence. Methods The cohort study was conducted for the 8 824 children from 3~5 years old who took part in the kindergarten entrance exam and followed up to 1 year.China Preschool-children Temperament Scale (CPTS) was used to evaluate baseline investigation and temperament type.Special cases management was used if diagnosed as asthma during the follow-up. Results A total of 8 824 children were selected,of which 4 738 were male,4 086 were female and their ratio was 1.16∶1,3~4 years old children accounted 94.38%; easy-educated type temperament children accounted 35.19%,and intermedial easy-educated type accounted 28.32%,difficulty-educated type temperament accounted 7.74%.The asthma incidence rate of difficulty-educated type temperament and intermedial difficulty-educated type temperament children were 7.17% and 5.53%,whereas slow-moving priming type temperament children were 1.12%.There was strong correlation between genetic factor and asthma.Difficulty-educated type temperament and slow-moving priming type temperament were strongly correlated to asthma occurrence(RR=1.53 and 0.26). Conclusion To avoid asthma occurrence,it is necessary to bring into full play the positive effect of temperament and limit the negativity effect of temperament and impulsive behavior.