We study the strain effect on the surface melting of Si(1 1 1) flat surfaces using Monte Carlo simulation and the empirical Tersoff-Dodson potential. The in-plane strain effect an the atomic structures and the atomic dynamics were investigated at a fixed temperature of 0.82T(m). Surface melting of Si(1 1 1) was induced by either compressive or tensile strain. As the strength of strain increases beyond the critical strength of about 1.5 and 2.5%, respectively, far compressive and tensile strain, the waiting time for surface melting decreases. In the lateral pair correlation function of the melting layers, only the nearest-neighbor correlation remains. Si atoms in the melting layers has a constant diffusion coefficient irrespective of the sign and strength of applied strain.