Many factors could impact the diffusibility of antimicrobial agent. 1g Nisin was added into chitosan to prepare the antimicrobial coating, and contacted 100 ml 2 %sucrose solution, 2 %NaCl solution and water respectively after coated on film. The diffusive volume of Nisin was measured by Coomassie brilliant blue method and the diffusion coefficient was calculated to evaluate the diffusibility of Nisin in different food stimulants. The result showed that diffusion coefficient of Nisin was the largest in 2 % sucrose solution, followed by water and 2 % NaCl solution.