Abstract: In order to analyze the variation pattern of reliability indicators of deep foundation pit under different correlation coefficients of soil shear strength parameters, the failure functions were established for anti-sliding stability,anti-overturning stability and anti-uplift stability of deep foundation pit, respectively, based on Copula theory and in combination with the modeling process of single failure mode. Then, the failure reliability of deep foundation pit system based on Copula theory was analyzed in series. The application results show that: anti-sliding stability and anti-uplift stability account for a major part of the system stability, while anti-overturning stability only accounts for a small part; Reliability indicators of the system under each failure mode may change significantly as function of the correlation of shear strength parameter, which proves that the influence of parameter correlation cannot be ignored in reliability design; Different copula functions have a great impact on reliability calculation. So, it is necessary to fit and optimize the distribution of parameters. The failure probability of the project may be underestimated if it is directly assumed that the parameters follow Gaussian distribution.