Abstract: The servo control system is a critical component of radio telescopes with high electromagnetic emissions. However, the distribution of different equipment across various locations of the telescope poses significant challenges to conducting electromagnetic interference (EMI) measurements under laboratory conditions. This paper addresses these challenges by conducting an on-site EMI assessment of the servo control system at the Nanshan 26-meter Radio Telescope (NSRT), providing technical support for further electromagnetic protection. First, the electromagnetic interference mechanisms of the servo control system were analyzed. Through on-site EMI measurements, data calibration, and environmental noise elimination, radiated emission spectra of different devices were obtained. Furthermore, based on the telescope's radiation threshold, an Entropy Weight Method (EWM) model was employed to evaluate the electromagnetic interference levels of various devices, determining their radiation levels and shielding requirements. Based on these results, this study further discusses feasible electromagnetic protection schemes and related considerations for the system.