The significant environmental improvement in China has drawn much research attention in recent years. However, in exploring the factors that lead to pollution reduction, most literature has ignored the slowing economic growth under the ‘New Normal’ of China. This omission could lead to the overestimation of the pollution reduction effects of other factors. In this paper, we estimate the effect of the economic slowdown using a dynamic Computable General Equilibrium model, CHINAGEM. We find that the contribution of the economic slowdown to pollution reduction ranges from 10% to 30%. This indicates the importance of considering the economic slowdown when evaluating the effects of other factors related to the environmental improvement in China.