The properties of a diode-pumped Nd∶YVO₄ continuous-wave laser operating at 1.34 μm with different resonator lengths were studied. The effects of thermal lens on the stability of cavity and the output characteristics were studied by calculating the laser mode size on the front surface of laser crystal. A simple planar-concave cavity was used. The maximum output power of 2.39 W was achieved at incident pump power of 7.56 W,with the maximum slope efficiency of 36.5% and optical conversion efficiency of 31.7%.