Abstract: In order to obtain a broadband tunable coherent sottrce,based on Mg0-doped periodically-poled lithium niobate,an optical parametric oscillator(OPO)was pumped by a 1064nm acousto-optically q-witched Nd: YAG laser,which can be conveniently tuned by means of changing its temperature.When the crystal temperature was adjusted from 40℃ to 200℃,the tunable mid-infrared output wavelength shifted from 1.565μN,m to 1.670μm.When the average pump power was 1.61w with about 70ns pulse duration operating at a repetition rate of 10kHz,the maximum signal output power of the OPO was about 211mW at 1631nm.It was shown from the results that temperature tunable optical parametric oscillator was a candidate of broadband tunable coherent sources.