This paper presents a controller based on Model-assisted Extended State Observer, aiming to address the challenge of suppressing parametric disturbances in non-minimum phase systems. By demonstrating the existence of equivalent input disturbance in the system with multiple input channels, it reveals the rationality of the proposed controller and the physical significance of the extended state. This paper derives the characteristic polynomial of the closed-loop system and analyzes the applicability of the proposed controller in two specific conditions. Through two representative case studies, it further substantiates the superiority of the proposed controller over the Full-order Extended State Observer-based control. The introduction of model-assisted techniques effectively resolves the issue of inherent input-parameter disturbances which is in the Full-order Extended State Observer-based control, providing non-minimum phase systems with an enhanced capability to suppress parametric disturbances.