An optical parametric oscillator based on periodically poled MgO doped lithium niobate ( PPMgLN-OPO) is reported.The output temporal characteristics of PPMgLN-OPO are discussed by varying its domain period and temperature tuning as well as pump power.In this experiment,the pulse width of pumping light and signal light is measured respectively by adopting MOTORULA′s Si-diode and JUDSON′s InGaAs diode as detectors.LD end-pumped Q-switched Nd∶YVO4 laser operating at a repetition rate of 19 kHz is used as pump source,when the pump power is 1 008 mW,PPMgLN-OPO produces the signal output power of 238 mW with the smallest pulse width of 9.3 ns,its optical-optical conversion efficiency is 23.6%,and the pulse width of signal wave is narrowed significantly.