The mixed Logit model is used to study the reliability of the civil systems engineering in combination with the civil engineering and the systems engineering. The SPSS software is used to make the statistical and reliability analyses of the survey data, and the key indicators that affect the reliability of the civil systems engineering are obtained. In the meanwhile, an appropriate mixed Logit model is established, and the multivariate statistical analysis software SAS is used for simulation and reliability analyses with respect to the three typical modes of civil systems engineering-DBB, PMC, and EPC. It is shown that the reliability index of DBB mode is 83.69%, while those of the PMC model and the EPC mode are 76.03% and 71.39%, which indicates that that DBB mode has the highest reliability. The results and the method provide a theoretical basis for the applications of the civil systems engineering modes.