The operational safety and health of key components of mechanical equipment are closely related to the temperature status. Aiming at the limitations of traditional single-point temperature measurement schemes that are difficult to capture the dynamic heat flow field, this paper proposes a multi-channel acquisition system based on thin-film resistance temperature detectors （RTD） sensors. The system aims to overcome the inherent defects of the on-resistance of the analog switch and the wire impedance on the accuracy constraints in the existing multi-channel acquisition. Innovatively, a three-wire system combined with a dual analog switch differential compensation architecture is complemented by a dual constant current source structure to effectively eliminate the effects of wire impedance and analog switch on-resistance. In addition, the polynomial fitting algorithm is utilized for real-time software compensation to further eliminate the resistance residual deviation. The experimental validation shows that the system can test the thin-film RTD sensors within the temperature zone of 20℃~300℃ with a resolution of 0.07℃ and an accuracy of better than 0.4℃, which is capable of providing highly reliable temperature field data for the structural health monitoring system of the key components, and improving the accuracy of the structural condition diagnosis of the mechanical components.