研究了激光在厚介质中的传输特性以及激光与原子相互作用的光电离。推导了三步光电离的场方程组和原子布居的密度矩阵方程组。计算了在不同情况下电离几率与激光参数的变化关系。深入研究了激光在厚介质中传输引起激光参数的变化，以及激光功率、脉冲形状、脉冲宽度、三束激光的时间不同步对电离几率的影响。 The transmission properties of laser in thick medium and the photoionization of laser interacting with atoms are studied. Derived three-step photoionization field equations and atomic population density matrix equations. The relationship between ionization probability and laser parameters under different conditions was calculated. The effects of laser parameters on the laser parameters, such as laser power, pulse shape, pulse width and the time lag of the three laser beams, on ionization probability are studied.