The wavelengths of 1 064 nm, 532 nm and 355 nm single-pulse laser were used to irradiate the polysilicon to study the interaction between different wavelengths of laser with polysilicon material systematically. The damage patterns of the polysilicon under the three laser wavelengths were studied. Experimental results shows that: with other parameters unchanged, the damage threshold decreases with the laser wavelength becomes smaller and it has linear relationship with laser wavelength; At low energy density level, the model of the interaction between the wavelength of 355nm laser and material is photochemical model based on the photochemical-photothermal common mode of action and it is light and heat model for other wavelengths; When the laser energy density is in low level, the interconnected regular hexagonal microstructure appears in the irradiated area. The center of the hexagon presents circular convex status. It is generated by nature of lateral flow fluctuations of the liquid and it has relation with the roughness of the polysilicon surface.