The influence of pump wavelength on output power of 1064 nm laser is experimentally investigated. When the wavelength of pump source is 808 nm, the maximal output power of laser is only 20 W. However, when the wavelength of pump source is 888 nm, the maximum output power of 1064 nm laser can reach up to 33.7 W. In that case, the laser can work with single-longitudinal-mode owing to the nonlinear loss induced by the frequency doubling crystal in the resonator. The measured long term power stability and M2 are better than ±0.51% and 1.1, respectively.