High quality GaAs films with dislocation densities of (1–2)×106cm−2on (100) Si substrates have been obtained for a combination of strained‐layer superlattice (SLS) insertion such as InGaAs/GaAs, InGaAs/GaAsP, and AlGaAs/GaAs and thermal cycle annealing using the metalorganic chemical vapor deposition method. Remarkable reduction effects of dislocation density and dislocation generation in the GaAs layers due to SLS insertion on Si have been analyzed by a simple model, in which coalescence and generation of dislocations are assumed to be caused by dislocation motion under misfit stress of SLSs. Misfit stress dependence of dislocation density reduction in GaAs films on Si has been clarified using this model.