A flash lamp pumped Ce3+-Nd3+ double doped YAG crystal water cool laser is devised, in which the La3Ga5SiO14, a novel electro-optic crystal activized by a field effect transistor (FET) fast switch circuit, is used as Q-switch. Based on above fact, steady 1.064 μm laser pulse eradiated at a repetition rate of 20 Hz is realized. An optical parametric oscillator (OPO) is designed outside the 1.064 μm laser resonant cavity, KTP crystal is employed to actualize optical parametric conversion, based on class Ⅱ non-critical phase matching 1.57 μm eye-safe laser is accomplished. Investigation and test is carried out about the influence of fixing stress of YAG rod to the output of 1.57 μm laser, a concernful phenomenon that double refraction induced by stress can depress the OPO conversion efficiency enormously, is discovered, the reason of efficiency fall is analyzed, the relation curve of equivalent stress and OPO conversion efficiency is presented. The highest OPO conversion efficiency is obtained at the pulse repetition rate of 20 Hz, when 1.064 μm laser pulse energy is 220 mJ, 1.57 μm laser pulse energy is 109.3 mJ, pulse duration is 4.3 ns, beam divergence angle is 8.1 mrad, OPO conversion efficiency reaches 50% nearly, corresponding electro-optic efficiency is 0.96% with an electric injection of 11.3 J, OPO efficiency falls slowly when 1.064 μm laser pulse energy increases much more. The energy stability of the OPO laser is excelled 5% with a smart configuration, environmental applicability including temperature, oscillation, impact etc is tested, engineering application of the OPO laser is realized.