【摘要】Based on the rate equation of four-level system and numerical simulation, the phase-matching characteristic of laser-diode-pumped Nd:GdVO_4/KBe_2BO_3F_2(KBBF) solid-state laser has been studied. The influences of pumping and oscillating spot size to output power and laser threshold with different gain medium are studied. Compared to CsLiB_6O_(10) (CLBO) and β-BaB_2O_4 (BBO), the phase-matching characteristics of the nonlinear optical crystal KBBF are carried out through numerical simulation. For type Ⅰ and type Ⅱ phase-matching condition, KBBF which is more easy to realize ultraviolet laser output has more shorter transmission bandwidth and more broader tunable phase-matching angle than CLBO and BBO. It is useful to optimize and select the parameters of such systems.