Due to the fact that cascade control can improve the single-loop's performance well and reduce the integral error from disturbance response, it has been one of the most important control strategies in industrial production, especially in thermal power plant and chemical engineering. However, most of the existing research is based on the Gaussian system and other few studies on the non-Gaussian cascade disturbance system also have obvious defects. In this paper, an effective control loop performance assessment (CPA) of cascade control system for many non-Gaussian distributions even the unknown mixture disturbance noise has been proposed. Compared to the minimum variance control (MVC) approach, the minimum entropy control (MEC) method can obtain a more accurate estimate. In this method, like MVC, the primary loop output and secondary loop output can be represented as invariant and dependent terms, then adopted estimated distribution algorithm (EDA) is used to achieve the system model and disturbances. In order to show the effectiveness of MEC, some simulation examples based on different perturbations are given.Symmetry 2019, 11, 379 2 of 15 whatever delay time is known or not. Then more research had been done in this field. In 1996, Harris proposed a performance evaluation method for a multiple-input multiple-output (MIMO) feedback control system [7]. Although the MVC controllers can meet the control performance requirement, the system robustness perform poorly. Hence, a generalized minimum variance (GMV) concept was raised by Grimble, he used this benchmark as single-loop CPA index and designed the corresponding controller based on GMV concepts. Unfortunately, it is necessary to add errors and control weighting factors to the control loop. Unless a fixed weight value is used, it is difficult to choose the appropriate weighting factor unless a constant weight is used. Huang and Shah presented a linear quadratic Gaussian (LQG) benchmark based on the MVC method [8]. Since the minimum variance of the output is only calculated compared to MVC, LQG also needs to calculate the minimum variance of the input, so for the same system, the LQG benchmark can better reflect the gap between the current actual performance and the ideal performance. However, compared to the traditional MVC benchmark, LQG is too complicated to implement in real industrial processes. In addition, many new CPA means has been put forward with further research. Such as the Hurst index is presented by Srinivasan, although it requires no prior knowledge [9,10], under the mixture noise environment this method may cause severe error. Sadasivarao tried to import the generic algorithm to cascade control loop to design optimal PID controller [11]. Yu uses CPA tools to get random sample jitter to show performance impact [12]. Ye presented a method about how to design the optimal cascade loop [13].Although all these methods have been quite mature, all previous research on CPA was based on the assumption that interference interferes with Gaussian distribution. I...