Choosing the middle school students in shanghai as the testees, the research revised the reliability and validity materials of PESIS of the Chinese version, and proposed a model of the situational interest, so as to measure the different factor’s influence to the situational interest. Through the test and analyze the situational interest during the testees’ learning, the major factors and the interactive relations between the different dimensions was discovered. The results of the researches showed that the PESIS of the Chinese version had the stable reliability and better validity, the six factors construct is eligible, which can predict the total variance well; the correlation and the regression analysis showed that the instant enjoyment was the major factor to invoke the PE situational interest, on the other side, too high novelty and challenge of the learning content will diseased the situational interest.