Reforming business tax(BT) as value-added tax(VAT) is a major institutional innovation, which not only will reduces the company’s tax burden, but also works in concert with China's majors strategy such as the change of economic development mode, innovation-driven development and so on. It has great significance and plays important role. This paper takes the listed companies of information technology service as the research objects and chooses the corresponding data from 2010 to 2015 as the research sample, studying the relationship between "BT to VAT" and enterprise innovation from the perspective of financing constraints with the model of multiple regressions. The study found that "BT to VAT" can promote independent innovation, and alleviate the inhibitory effect of financing constraints on enterprise innovation.