The work aims to study the influence of different restraint layer materials on surface strengthening effect of laser peening. Laser shot peening technology was applied to strengthen the surface of 7075 aluminum alloy, laser peening experiment of the 7075-T6 aluminum alloy was carried out with self-developed flexible restraint layer, K9 glass, water layer as restraint layer materials, and surface micro-hardness of the laser peened specimens were measured to study surface strengthening effect. Single-point single-pass impact was conducted provided with parameters as follows: laser energy of 1.6 J, pulse width 10 ns and wavelength 1064 nm. Under this circumstance, surface strengthening effect of the self-developed flexible restraint layer was the best, surface microhardness value of the laser peened specimens increased by 11.62%. After continuous laser peening, the surface microhardness increased by 18.11%. Surface strengthening effect of the restraint layer made of water layer took second place, surface micro-hardness value of the laser peened specimens increased by 6.99%, and water splash might easily be produced. Surface strengthening effect of the restraint layer made of K9 glass took second place was the worst, surface micro-hardness value increased by 4.05% only, and the K9 glass may be broken easily. Influence mechanism of different restraint layer materials on the strengthening effect of 7075 aluminium alloy is found to be different based on analysis and comparison of laser peening experiment results. The self-developed flexible restraint layer has the best surface strengthening effect on 750 aluminium alloy laser peening and is of engineering application value.