In many application cases, a huge system can be decomposed into several small systems connected in series. . For example: In the process industry, the processing flow of materials is often a series connection of several sets of devices or units. For the optimization of systems with significant lag, the time constant from the optimization variable to the objective function is large. If it can be physically divided into several small systems in series, or referred to as cascading, and processed separately, better results may be obtained. Apparently, the dynamic correlation integration method of cascade systems need to be studied.