Passively Q-switched mode-locking Nd∶Gd0.42Y0.58VO4 laser is successfully demonstrated by using a piece of GaAs crystal grown at low temperature (LT-GaAs) as the passively saturated absorber as well as the output coupler. The fundamental properties of Nd∶Gd0.42Y0.58VO4 laser are investigated. At transmission of 10% and cavity length of 40 mm, the maximum average output power of 3.78 W is obtained when the incident laser pumping power is 8.6 W, which corresponds to an optical-optical conversion efficiency of 43.9%. The output performance is then tested for the passively Q-switched Nd∶Gd0.42Y0.58VO4 mixed crystal laser. The threshold power for Q-switching and Q-switching mode-locked (QML) are about 2 W and 3.7 W respectively. At the incident laser pumping power of 8.6 W, Q-switching mode-locking pulse with modulation depth more than 70% is available. The Q-switched envelope train with repetition rate of 670 kHz is obtained with pulse duration of 180ns. The average output power and the optical-optical conversion efficiency are 1.35 W and 15.7%, respectively.