Abstract: The changes of microstructrue and mechanical properties of 00Cr25Ni7Mo3N duplex stainless steel have been studied at different solid solution temperatures by using metallographic image analysis.The experimental results showed that in this paper:①A large number of σ phase on phase boundary of austenite and ferrite precipitated at 900~980℃,leading to the decrease of plasticity and toughness of steel;②When the solid solution temperature is higher than 1 000℃,σ phase dissolved gradually with the temperature increase further,the ratio of α phase increased sharply,the plasticity and toughness of steel increased gently;③Appropriate phase scale and mechanical property are obtained for 00Cr25Ni7Mo3N in the temperature range of 1 000~1 100℃.