The model of NPVGO indicates PER plays an important role in investment analysis and decision, which reflects stock returns and risks, conveys information about a company's growth and profitability. However, data from China A-Share stock market states that lacks of Value-Investment concept make PER ineffective to reflect a company's growth and profitability; PER can just be a consultative target. Only by improving supervision mechanism in stock market, establishing information disclosure system, setting up the value-investment concept, and setting up a more effective market, can PER be decisive.