Aiming at the real-time requirements for industrial control systems, we proposed a corresponding trust chain method for industrial control system application software and a component analysis method based on security sensitivity weights. A dynamic length trust chain structure is also proposed in this paper. Based on this, the industrial control system software integrity measurement method is constructed. Aimed at the validity of the model, a simulation attack experiment was performed, and the performance of the model was repeated from multiple perspectives to verify the performance of the method. Experiments show that this method can effectively meet the integrity measurement under the condition of high real-time performance, protect the integrity of files, and improve the software credibility of industrial control system.