The interaction process of a high-power laser and a PIN junction optoelectronicdiode has been studied theoretically and experimentally.It has been put forward that thethermal effect of the laSer beam and the eroding and washing effect induced when the laserplasmas expend out result in the damage of the silicon photodiode.The thermal distributionand an expression of the maximum temperature have been obtained or the first time whenthe Q -switched Nd:YAG laser irradiates upon the PIN junction optoelectronic diode.