Laodelphax striatellus is an major pest on rice in China. It has strong adaptability to environments and was found in all rice growing areas of the country. As a molecular chaperone, HSP70 plays an important role in biological growth and response to stress. HSC70,characterized by constitutive expression, is one of the most important members of the HSP70 family. To explore the adaptation mechanisms of L. striatellus to environments, LHSC70 expression profiling and function were analyzed. The results showed the complete cDNA of LHSC70 is 1971 bp in length, which encodes a protein of 656 amino acids, with a molecular weight of 71.6 kD and theoretical isoelectric point of 5.46. LHSC70 contains three signature sequences of HSP70 family and carries a typical HSP70 family structural signature. The phylogenic tree showed it shares 99% homology with HSC70 of Nilaparvata lugens. The expression of LHSC70 was associated with larval instar. The expression level of LHSC70 was highest in female adults and was similar in male adults and larvae at various instars. The difference in the expression of the gene was not significant after 10, 16, 22, 26, 30, 34, 38 and 42℃ treatments. Downregulated expression level of LHSC70 due to RNAi significantly decreased the tolerance of the female to heat stress, while exerted a less influence on the oviposition. These results suggested that LHSC70 is a 70 kD heat shock cognate protein and is not induced by heat stress, but it contributes the constitutive resistance to heat without close relation to reproduction in L. striatellus.