In control engineering, there may be two systems that have the same input-output characteristic with differentdegrees of complexity. This concept leads to order diminution(OD) of a large scale system. In this article, the authorspropose a new hybrid order diminution technique based on the time moment matching method with the Routh arrayconcept and a recently developed fast and accurate salp swarm optimization (SSO) technique. The proposed methodcombines the advantages of both the classical method of OD and the optimization technique. The unknown coe?icient ofthe divisor of the reduced system is obtained by exploring the time moment matching methodology with the Routh arrayconcept, whereas the unknown coe?icients of dividend polynomial are obtained by the SSO technique. The time momentmatching with the Routh array ensures the nature of the system in terms of stability, and better search capability of theSSO technique reduces the error between the original and the diminished system. The proposed technique is tested ondifferent benchmark problems, including a time-delay system. An intensive comparative study in terms of different errors,time, and frequency domain provides better performance of the proposed method compared to the existing techniques. Agood match to the parameters of transient specifications indicates the success of this proposed technique. Comparatively,the matching of rise time, settling time, and maximum overshoots are 99.6076%,99.1611%, and 100%, respectively.