The stability and bacteriostatic effects of chitosan under different treatment conditions were studied. Escherichia coli and Staphylococcus aureus were used as experimental bacteria. The main influencing factors include chitosan concentration(chitosan concentration from 0 to 20 grams per liter), temperature(ice bath, 25℃, 60℃, 121℃), Metal ion species (NaCl, MgCl.2, FeCl.3) and concentration(0.1 mol/L, 0.2 mol/L, 0.3 mol/L, 0.4 mol/L, 0.5 mol/L), acid solvent(HAc, HCl, citric acid). The antibacterial effect of each influencing factor was determined by filter paper agar diffusion. The results show that with the increase of chitosan concentration, the bacteriostatic effect was enhanced, and chitosan has good stability at different temperatures. Metal ion species and concentration have certain inhibiting effect on the properties of chitosan. The chitosan dissolved in different acid solvent, its stability and antibacterial effect were different.