High-temperature environments can significantly affect the performance of electrical connectors, making the quantitative analysis of the impact of high-temperature oxidation on contact resistance become an important research topic in electrical connector design. This article conducted high-temperature oxidation experiments on connectors with three plating metal: gold, silver, and tin. We established a composite multivariate function model of contact resistance R with respect to oxidation temperature T, contact normal force F, and oxidation time t. With the coefficient of determination greater than 0.8, the model effectively predicts the degradation trend of contact resistance, evaluates connector reliability, and provides guidance for optimizing contact normal force design in connectors.