Due to the lack of outfield failure data and historical warranty claim records of new products, it is difficult to carry out scientific and reasonable warranty cost prediction and warranty period optimization. Considering the interaction between the degradation processes of different product performance parameters, this paper proposed a method for the design and optimization of the warranty period of new products with two-parameter degradation based on Copula theory. Firstly, a single parameter performance degradation model was established according to the laboratory accelerated degradation test data. Copula theory was used to quantify the correlation between degradation processes. In addition, the outfield reliability model was given by quantifying the dynamic operating environment of the outfield. Secondly, the maintenance improvement factor model was used to quantify the imperfect maintenance situation in the process of maintenance, and the Monte Carlo simulation was employed to calculate the predicted number of product failures. Moreover, the warranty cost model was established. Then, the Glickman-Berger model was used to quantify the impact of the warranty period on product sales, and an optimization model of the warranty period was constructed to maximize the manufacturer’s profit. Finally, by taking a certain type of electronic component as an example, the design and optimization of the warranty period of products and sensitivity analysis were carried out to verify the validity and applicability of the model.