In literature, the firm’s selection of dual-product strategy under cap-and-trade regulation and the optimal emission reduction decisions are not well studied, especially through an analytical approach. We develop a theoretic model to investigate the firm’s selection on three product strategies in the presence of cap-and-trade policy, including two single product strategies and a dual-product strategy, and identify two types of consumers: consumers with low-carbon preference and regular consumers. Our analysis shows that, (i) in the absence of cap-and-trade policy, it is optimal to adopt dual-product strategy, but in the presence of this policy, it is optimal to adopt dual-product strategy or low-carbon product strategy. (ii) Compared with ordinary product strategy, adopting a low-carbon product strategy or dual-product strategy benefits the firm under cap-and-trade regulation. (iii) The additional cost of producing low-carbon product has an impact on the firm’s product strategy selection under cap-and-trade regulation. When it falls below a certain threshold, it is optimal to adopt a dual-product strategy; otherwise, it is optimal to adopt a low-carbon product strategy. Our research can provide reference for firm’s decision-making and government’s policy formulation.