In this article, a new method for the simplification and controller design for large-scale linear dynamic plants is proposed. This method is applicable for both large-scale single input single output (SISO) and multiple input multiple output (MIMO) models. The diminution procedure is simple and it assurances the stability of the lower-order plant provided that the higher-order system (HOS) is stable. The characteristic equation of the desired system is evaluated by using the stability equation technique and the coefficients of the numerator polynomial are calculated by applying a simple mathematical process as mentioned in the proposed scenario. This algorithm is suggested for circumventing the limitations of the stability equation scheme and preserving its important features such as stability, passivity, etc. The proposed method ensures the retention of stability and static characteristic of the higher-order plant in the reduced model. For validating the accuracy and effectiveness of the proposed technique, it is implemented on the three standard real-time systems. These systems are further used for the comparison of the proposed method with some other popular existing algorithms. By using the proposed lower-order plant, a controller is obtained for the large-scale system with the help of the moment matching technique. The design of the controller is demonstrated and validated by a real-time system taken from the literature.