Panel data of 234 cities in China from 2011 to 2018 is used to measure the urban shrinkage index. PM2.5 is used as an indicator of haze pollution, and labour supply is the mediator. On this basis, the influence mechanism of haze pollution on urban shrinkage is analysed theoretically. Next, using the dynamic panel model and the mediating effect model, we empirically examine the impact of urban shrinkage on haze pollution and the mediating effect of labour supply. The main findings are as follows: haze pollution increases the degree of urban shrinkage, and labour supply plays a regulatory role in the process of haze pollution affecting urban shrinkage. According to our research, pertinent policies and suggestions are proposed to reduce both urban shrinkage and haze pollution.