To study the influence law of purified cotton quality and nitrification process on the nitrification uniformity of nitrocellulose (NC) with high-nitrogen content, purified cottons with different maturity were nitrified via H₂SO₄-HNO₃-H₂O system, and NC with high-nitrogen content was prepared by changing sulfuric acid-nitric acid ratio and nitrification time. The nitrogen content and nitrification uniformity of NC were measured by polarizing microscope. The influence law of different maturity and nitrification processes on the nitrogen content and nitrification uniformity of NC with high-nitrogen content was discussed. At the same time, typical gun propellants were suppressed via. gelatinization of NC with different uniformity, and the microstructure of the lateral cross sections of the corresponding granules was compared. Results show that the nitrification uniformity of NC prepared from purified cottons with high maturity is better than that of low maturity products. NC prepared by low sulfuric acid-nitric acid ratio as 2.7 has higher nitrogen content and better nitrification uniformity. Using purified cotton of maturity as more than 70% as raw material, the nitrification uniformity index-variance of prepared NC is about 2.3. When nitrification time is about 30 mins, the nitrification effect is the best, the prolongation of nitrification time only has a little effect on the nitrogen content, but the uniformity decreases. So through the control of sulfuric acid-nitric acid ratio in the nitrification system and nitrification time, using purified cotton of high maturity as raw material, the NC with better uniformity can be obtained and the gelatinized extrusion molding quality of high-uniformity NC-pressed single-base propellant is significantly improved.