The tax Principle of legality emphasizes that when a country levying tax, it must be definite and have a basis on law. Implementing the tax principle of legality is the core and foundation of improving our country’s tax law system, and it is also a focus that we must take attention in the future development of our country. In view of various reasons, in our count country,there are many difficulties and challenges when Implementing the tax principle of legality. At present, in order to Implement the tax principle of legality, we need to take measures such as establish the tax principle of legality in constitution, make the tax law enforcement more normative, perfecting the legal relief system of taxation and so on.