This study centres on how demand uncertainty impacts emission reduction in supply chains, premised on the Stackelberg game model.It delves into the collaborative emission reduction and pricing strategies of a four-echelon supply chain, including suppliers, producers, retailers and consumers, and meticulously examines the function of producers' carbon emission reduction subsidies and low-carbon product promotion subsidies in this process.The findings indicate that producers' reduction subsidies to suppliers and promotion subsidies to retailers play a coordinating role in supply chain emission reduction and product pricing, either directly or indirectly.The promotion subsidy for products with lower carbon emissions strengthens retailers' efforts to promote them and increases retail prices.Although these subsidies might lower producers' emission reduction levels and raise wholesale prices, they enhance the entire supply chain system's emission reduction.