Abstract: This article discussed the practicability of acid-heating method which could break Aspergillus niger's cell walls in order to extract chitosan.Based on the single factor test analysis, the effects of three variables, which including cell wall breaking temperature, cell wall breaking time, and concentration of hydrochloric acid on the technology of breaking Aspergillus niger cell wall and the optimum process were evaluated by Box-Behnken central composite experimental design and response surface methodology analysis.The results indicated that cell wall breaking temperature of 100℃, cell wall breaking time of 1.6h, and concentration of hydrochloric acid of 2.1% were the optimum condition.The experimental values of chitosan yield were 10.87%, and the relative error with the theoretical value 11.06% was 1.72%. Therefore, the chitosan extraction from Aspergillus niger optimized by response surface methodology was very reliable.