Abstract: Taking the listed A-share heavily polluting enterprises in 120 major cities in China from 2011 to 2019 as the research object, this paper empirically tests the impact of reducing corporate tax burden and implementing strict environmental supervision on environmental protection investment of enterprises. The study shows that the reduction of tax burden can promote the increase of environmental protection investment, and the strict environmental supervision can further strengthen the promotion of environmental protection investment. The further study shows that the strengthening effect of environmental regulation is pronounced more in the Midwest than that in the eastern regions. Moreover, it suggests that in response to the long-standing problem of insufficient investment in environmental protection in heavily polluting enterprises in the Midwest,tax reduction policy with incentive function and environmental supervision mechanism with supervision function can play a joint mitigation role from the macro level.

Key words: tax reduction, environmental regulation, environmental investment, strengthening effect, cost-benefit