This paper analyzes entrepreneurs' exaggerating of product quality and the related precautions by using theoretical models. Theoretical models for the initiation stage and selling stage of the pre-order crowdfunding are constructed. By solving the optimization problem of entrepreneurs,the optimal crowdfunding price and product quality promised to investors are given,and the incentives for entrep,reneurs to exaggerate the product quality are analyzed. On this basis,this paper designs precautions consisting of margins and credit constraints,and analyzes their preventive effects on entrepreneurs' exaggerating product quality. The results show that: Entrepreneurs exaggerate the product quality in order to make crowdfunding successful and maximize theirreturns without precautions. Crowdfunding platforms' collecting margins can prevent entrepreneurs from exaggerating product quality,but with limited preventive effect; Adopting credit constraints can make up for the shortcomings of margins and improve the preventive effects. Finally,a numerical analysis elaborates the relevant results obtained by the theoretical model.