This paper conducts a systematic and multi-level study on vibration and noise source identification and engineering control practices for the abnormally high noise level near the operator’s ear in the cab of a new electric loader developed by Liugong during mass production. First, through rigorous comparative testing, noise spectrum data of the prototype and mass-produced machines under identical operating conditions were collected. Based on detailed spectrum analysis and coherence analysis, the hydraulic system was successfully identified as the primary noise contributor. To further investigate the root cause and verify potential solutions, a comprehensive testing and analysis system was established. This method integrated high-precision acoustic measurements (near-field sound pressure method) and multi-channel vibration testing (vibration acceleration measurement), enabling synchronous monitoring and correlation analysis of noise sources, transmission paths, and response points. On this basis, a series of comparative validation tests were designed and implemented. The results indicate that the use of an internal gear pump or optimization of the connection stiffness and installation method of the confluence flange can significantly reduce the cab noise level under all operating conditions, effectively resolving the engineering problem of inconsistent noise performance between mass-produced machines and prototypes. This study establishes and validates a systematic diagnostic methodology and effective engineering solutions for NVH issues in hydraulic systems of electric construction machinery, providing a valuable practical reference and theoretical basis for low-noise hydraulic system design and noise problem mitigation in similar electric loaders and other electric construction machinery.