Based on 139 industrial internet of things (IIoT) listed companies from 2014 to 2019, this paper conducts empirical research to further explore the impact of industrial subsidy policies mainly from two aspects: companies' R&D investment and revenue growth. The result shows that policy subsidies directly support companies' R&D investment, especially for industrial and private enterprises; whilst policy subsidies and companies' revenue growth are not significantly related. This indicates that policy subsidies have not been effectively transmitted to corporate performance. It is found that China's IIoT industry has achieved a rich level with various applications and multiple industrial platforms. Additionally, a well-structured policy framework has been realised. However, China's IIoT industry, whether in terms of volume or competitiveness, has a gap with the world's leading development level. This paper also proposes three suggestions for supporting IIoT policies in the conclusion.