Objective In this paper, the optimal process conditions of electroless nickel plating in hydrazine-ammonia complex system were studied. Methods With chitosan as a pretreatment agent, the influences of the concentration of each component in the plating bath and the processing conditions were discussed. Results The optimal process conditions were as follows: the concentration of nickel acetate 45 g / L, the concentration of hydrazine hydrate 20 g / L, the concentration of ammonium sulfate 8 g / L, the pH value of bath 9 , the temperature of electroless plating 75 ℃ , the time of electroless plating 2 h. Conclusion In this reaction system, polyamide fiber modified by chitosan can obtain thick and firm adherence electroless pure nickel coating, and lower square resistance, under the optimal technological conditions.