Based on the miniaturized multi-wavelength selective output Nd∶YVO4 solid self-Raman laser, the thermal stress distribution within the laser crystal was theoretically analyzed, and the locations where the thermal cracking easily occurs were obtained, which is consistent with the experimental results. An experimental platform was set up to study the effects of laser crystals on the laser output power at various wavelengthes after thermal cracking. Experimental results show that the threshold and output power of the 1064 fundamental frequency laser before and after thermal cracking do not change much, but the laser threshold at 532, 559 and 588nm increases from 0.2 to 0.43W, 0.3 to 1.5W and 0.3 to 1.5W, respectively, while the maximum output power is reduced from 560 to 131mW, 600 to 50mW, and 200 to 26mW, respectively.