The calculation provisions in Chinese design codes for excavation for determination of the embedded depth of cantilever retaining structure are disputed and the safety margin is not sufficient. The requirements in relevant Euro and British standards are theoretical correct but the traditional simplified method results in a conservative embedded depth. We summarize the basic rules for determination of the embedded depth of cantilever retaining structures，and analyze the problems of the relevant principles in Chinese and international design codes for excavation. We suggest that the partial factor method together with the strict load equilibrium and moment equilibrium conditions is used to calculate the embedded depth of cantilever retaining structure. The resulted embedded depth is larger than that calculated by Chinese standard，and is smaller than that calculated by the internationally accepted simplified method. The improved method is more rational in theory and can achieve a safe and economical design in practice.