Existing assessment methods for capacitor bank circuit breaker contact degradation still have certain limitations in practical engineering applications due to the lack of targeted online monitoring technologies and equipment. This paper proposes an online monitoring method for circuit breaker contact degradation based on the variation characteristics of pre-strike arc electrical parameters during closing operations. A full life-cycle contact ablation simulation and pre-breakdown characteristic test platform is established to simulate the ablation degradation process of contacts during long-term operation. Repetitive pre-strike tests are conducted under different contact degradation states to obtain pre-breakdown voltage and current waveform data and analyze the influence of contact degradation on pre-breakdown arc characteristics. On this basis

combined with the circuit breaker pre-strike arc model

a quantitative method for characterizing the variation degree of electrical parameters during contact degradation is proposed. An online monitoring method for circuit breaker contact degradation is constructed

including three monitoring characteristic quantities

namely

the peak current of pre-breakdown arc

the attenuation characteristics

and the pre-breakdown time. Field recording data validate the proposed method

demonstrating that the multi-parameter fusion approach for contact deterioration assessment achieves accurate state discrimination. The model features a concise structure compatible with on-site sensor networks. These findings provide critical theoretical supports and practical values for realizing online monitoring of circuit breaker contact deterioration.