In pulsed diode laser side-pumped solid-state laser, time-varying distribution of temperature in laser crystal is numerically calculated. Three-direction pumped beam intensity distribution in laser crystal is analyzed. Based on the solution, the temperature distribution and its influence in single-pulse process of pulsed diode laser array side-pumped Nd∶YAG laser is obtained by finite element method. The results show that the process of temperature rise is influenced by pump condition and cooling method, but the main influencing factor are the pump conditions such as pumping power and beam waist. Cooling process is influenced by crystal thermo-physical parameters, radius and cooling condition. After the transient temperature distribution has reached dynamic equilibrium, because of radius temperature gradient periodically changing with time, the optical path difference between center and edge beam is also periodically changing with time.