The invention provides a method for controlling the nitrogen content of a low nitrogen steel, a converter smelting process comprises the following steps: a ratio of high molten iron and low scrap steel is used, wherein the tapping temperature is no less than 1700 DEG C, ferrosilicon is used for preparing silicon to 0.4%, a gas cover is declined during a whole course of oxygen blowing period; the high carbon with carbon weight at 0.05-0.07% is used when tapping, carbon tapping can be carried out at a time, argon is not blown during the tapping process and at an argon station; a RH refining process comprises the following steps: the argon flow can be controlled at 150N1/h from vacuum-pumping, the deep vacuum treatment time is controlled in 8-12 minutes, static duration after adding an alloy is 7-9 minutes; argon is continuously blown during continuous casting, and argon is used for casting protection. The method of the invention can effectively solve the nitrogen addition problem in steel, the nitrogen sample content in the argon station is controlled at 0.0011-0.0013%, the nitrogen sample content after finishing the RH treatment is controlled at 0.0013-0.0015%, and the nitrogen sample content of the finished products is controlled at 0.0016-0.0020%, and the degrading and steel judgment accidents due to improper component of the finished product nitrogen can be thoroughly eliminated.