The passively Q-switched Yb:NaY(WO_4)_2(Yb:NaYW) laser is studied.By using Cr~(4+):YAG as the saturable absorber,a very stable pulse train is obtained.At a high pump power,the pulse to pulse timing jitter is measured to be less than 2%and the amplitude fluctuation is less than 4%.A Q-switched average output power of 2.3 W at1029 nm is generated with a slope efficiency of 33.9%;the one-dimensional intensity distribution of the laser facula is of the Gaussian type.The output repetition rate,pulse energy,pulse width and peak power are 33.3kHz,70 μJ,36 ns and 2.0 kW,respectively.The passively Q-switched process is simulated by solving the rate equations,the simulated results are in good agreement with the experimental data. The passively Q-switched Yb: NaY (WO_4) _2 (Yb: NaYW) laser is studied. By using Cr ~ (4 +): YAG as the saturable absorber, a very stable pulse train is obtained. At a high pump power, the Q-switched average output power of 2.3 W at 1029 nm is generated with a slope efficiency of 33.9%; the one-dimensional intensity distribution of the laser facula is of the Gaussian type. The output repetition rate, pulse energy, pulse width and peak power are 33.3 kHz, 70 μJ, 36 ns and 2.0 kW, respectively. The passively Q-switched process is simulated by solving the rate equations, the simulated results are in good agreement with the experimental data.