In order to determine the difference of small heat shock protein (sHSPs) expression in four maize (Zea mays L.) varieties with different endurance under combined drought and heat stress,and the effect of abscisic acid (ABA) and H₂O₂ on their expression,we used ‘Zhengdan 958’ with drought endurance,‘Xundan 20’ with heat endurance,‘Longyu 602’ with endurance to combined drought and heat stress,‘Zhuyu 309’ with sensitiveness to three stresses as experimental material.ABA and ABA synthesis inhibitor Flu (F),H₂O₂ scavenger KI (I) and sodium pyruvate (P) were used to study the influences of ABA and H₂O₂ on sHSPs expressions induced by combined drought and heat stress in maize leaves.The results were as follows:(1)The increases of six sHSPs such as sHSP16.9,sHSP17.2,sHSP17.4,sHSP17.5,sHSP22 and sHSP26 induced by heat stress and combined drought and heat stress were all more than that induced by control and drought;(2)sHSP17.2 was only expressed in ‘Zhengdan 958’,while the increase of sHSP16.9,sHSP17.4 and sHSP26 gene expression was all the highest in ‘Longyu 602’,but the lowest in ‘Zhuyu 309’ among four maize varieties;the increase sHSP17.5 and sHSP22 gene expression was the highest in ‘Zhengdan 958’,but the lowest in ‘Zhuyu 309’;(3)The pretreatment with ABA,F,I and P,all slightly affected the increase of six sHSPs genes expressions,but significantly affected the increase of sHSP26 protein expression by heat stress and the combination of drought and heat stress.Our results showed that there was great difference of six sHSPs expression among maize varieties with different endurance.ABA and H₂O₂ slightly improve these sHSPs genes expressions,but significantly improve sHSP26 protein expression under the combination of drought and heat stress.These results lay a foundation for further investigating the mechanisms of plants tolerance to combination stress.