Abstract: Research source of the problem: Global warming has become a great concern of the international community, and governments have taken measures to reduce greenhouse gas emissions. Most of economists put forward that carbon tax is an effective method to reduce carbon emission, which will significantly affect the manufacturer's production-related decision-makings. Thus, to maximize profitability, it's particularly important for enterprises to choose an optimal strategy.Description of the problem: The decision-making of carbon reduction technology (CRT) adoption is considered in two competitive supply chains, each consisting of one manufacturer selling a homogeneous product to one exclusive retailer. The manufacturer needs to make the decision of CRT by comparing profits in different situations and considering the strategy of competitors. The functionC(e_i)=ke_i²/2 is used to describe the carbon emission reduction cost. Given that the manufacturer decides on wholesale price w and carbon emission reduction rate e, the retailers compete under Nash game and decide on ordering quantity q.Methods model of research: There is a two-stage Stackelberg game where the manufacturer is the leader and the retailer is the follower. Firstly, manufacturer decides the adoption carbon and wholesale price. Then retailer decides its optimal retail price according to the manufacturer's decision. For the all strategies and situations, the players’ optimal decision-variables, revenues and the equilibrium strategies of CRT adoption in competitive supply chains are derived.Problem-solving ideas: Four possible CRT adoption structures are created: Scenarios NN (no CRT adoption), AN (only supply chain 1 adopts CRT), NA (only supply chain 2 adopts CRT) and AA (both adopt CRT). By comparing with profits of different situations, then the manufacturer will decide whether adopts CRT. And based on strategy of the manufacturer, the rival manufacturer will make the optimal strategy to achieve win-win.Research results: It is found that when the carbon tax is low, Scenario AA is the equilibrium strategy for the supply chains. When the carbon tax is moderate, the high unit production cost supply chain forgoes CRT while the other chain adopts CRT to enhance his competitive power. When the carbon tax is high, Scenario NN is the equilibrium strategy. Furthermore, the government could increase carbon tax with weak competition supply chains, while choose abatement of carbon tax to make the supply chains to adopt CRT in a fiercely competitive market.The introduction of case data: The data in the article are referenced with former related papers in a portion. Thus, the results of numerical analysis in this paper can reflect the reality better.Contributions: This paper focuses on not only the carbon tax and carbon emission reduction technology, but also the chain to chain competition. In addition, the research ideas of this paper can provide reference for the related paper about competitive supply chains on carbon tax.

Key words: competitive supply chains, carbon reduction technology, carbon tax, stackelberg game, equilibrium strategies