资本资产定价模型（CAPM）被认为是金融市场现代价格理论的支柱之一，自从创立以来，其在各个领域得到了广泛的应用。然而，长期以来对CAPM的实证检验也争议不断，检验结果毁誉参半。本文评述了以往对CAPM的实证研究，并采用上海股票市场90家上市公司的数据作为样本对CAPM中的贝塔系数的波动状况进行了实证检验，结果发现所有股票贝塔系数的波动率都是显著异于零的，即贝塔系数在不同的时期会发生变化。实证分析中如果忽略了这一点，必将导致对CAPM检验失效。 Capital Asset Pricing Model is the backbone of the modern asset pricing theory of the financial market. Since it appeared, it is widely used in many fields. However, there are many disputations about the empirical tests of CAPM. Someone support it, but someone not. The authors review the past empirical tests of CAPM, and analyze 90 public companies in Shanghai security market. The conclusion helps to explain why some empirical tests of CAPM in the past fail.