Although ‘Cap-and-trade’ mainly constrains the manufacturer, the decision of the manufacturer’s emission reduction will affect the decision of the whole supply chain. In this paper, we investigate manufacturer and retailer’s decision under decentralized decision and centralized decision and taking into account the impact of carbon price and consumer environmental consciousness. Specially, we analyse the condition of whether a manufacturer transfers the emission reduction task to retailer. Besides, we use computational experiments to analyse the sensitivity by changing the cost function. Through the research, we have some findings: under a decentralized decision, manufacturer transfers emissions reduction task in more times, if the manufacturer transfers the emissions reduction task, the effectiveness of the emissions reduction, demand, retailer’s revenue per product and consumer welfare decrease. Under centralized decision, the manufacturer does not transfer emissions reduction task all time, which is affected by emissions reduction cost of the manufacturer and retailer, carbon price and consumer environmental consciousness. In addition, emissions reduction cost function is not the sensitivity factor.