The influence of the tilt angle of the intracavity etalon on the output longitudinal mode distribution of Nd:YVO₄ multi longitudinal mode laser was studied by rotating the linear laser intracavity gain medium.A theoretical model was established to analyze the effect of etalon effect on the output multi longitudinal mode characteristics of Nd:YVO₄ laser,and corresponding experimental research was conducted.In the experiment,longitudinal mode grouping and spectral drift phenomena were explored by rotating the crystal angle.The experimental results indicate that when the laser crystal angle increases from 0°,there are two phenomena:the broadening of the transmission peak linewidth of the etalon and the redshift of the longitudinal mode wavelength.The experimental results are in good agreement with the theoretical model.Finally,when the pump power was 2 768 mW and the laser crystal tilt angle was 0.45°,the etalon effect was successfully suppressed,and a mode-locked laser with slope efficiency and optical conversion efficiency of 15.66% and 13.9%,output power of 385 mW,and beam quality of 1.71 was obtained.At this point,by increasing the pump power,it was found that the spatial hole burning effect also produces an effect similar to the etalon effect.The experimental results also indicate that increasing the pump power will exacerbate the phenomenon of spatial hole burning.