Ab initio calculations of electronic structure for strained superlattices (SLS) （ＧａＰ）１（ＧａＡｓ）１（００１） and （ＩｎＰ）n（ＩｎＡｓ）n（００１）（ｎ＝１，３） are carried out, the valence-band maximum Ev and the average bond energy Em in each molecular layer of SLS's are investigated with the frozen shape approach. The average-bond-energy method for determining valence-band offsets at SLS's are suggestted and tested comprehensively. Based on this method, the valence-band offsets at five SLS's under three strain conditions are determined, their strain-induced effects are discussed. The results of present work show good consistency with available experimental data.