Polyeystalline InP films are deposited on SiO2 insulating substrate using a conventional EF sputtering equipment. The experimental results show a significant increase in grain size after Ar+ laser irradiation. Analysis of the stoichiometrical rate of InP by Rutherford backscattering spectrometry shows that the decomposition of InP is greatly suppressed by using a SiO2 encapsulant. Theoretical discussion on the recrystallization mechanism under Ar+ laser irradiation is presented.