从三个不同层次分析了影响市盈率的因素 ,指出评价一只股票是否有投资价值 ,不仅要看它本身的市盈率 ,而且要与同行业其它公司的市盈率相比较 ,更要与企业的未来发展相联系.选择一个投资对象 ,不仅要看它现在能创造多少利润 ,而且要分析它将来的发展空间 ,更要重视其作为上市公司的“壳资源”的价值及人们的心理预期“,”This article analyzes the factors that influence profit rate at three different levels. It points out that when dealing with an individual sock to decide whether or not it is worth investing, one should not only consider its PE, but also compare its profitability with other companies of the same trade, and also relate it with the company's future. To choose a company for investment, apart from its current profit, its potential growth, its value of “shell resources”, and the psychological expectation of investors should all be taken consideration.