Karst cave identification is crucial for ensuring the safety of shield machine construction and enhancing economic benefits. However, due to the sparsity of drilling data and the inadequacy of detection methods, karst caves still cannot be detected either partially or completely. Depending solely on a single shield machine parameter is inadequate for identifying the type of karst cave. For this purpose, a karst cave type identification index (Thrust and Soil Pressure Efficiency, TSPE) calculated through real-time shield machine parameters is proposed. First, the force conditions required to maintain the stability of the cutterhead face were derived based on the principle of soil pressure balance. Then, analyzes shield machine parameters related to this process and establishes TSPE. Finally, the accuracy and effectiveness of TSPE were validated through comparison with existing indices in practical applications. The results demonstrate that TSPE not only distinguishes geological types but also effectively differentiates types of karst cave fillings. However, this index cannot identify fractured zones in rocks with high integrity coefficients. Thus, TSPE enables engineers to timely identify types of karst caves and make necessary adjustments.