Abstract: Using tangerine as materials, combined the bacteriostatic properties of mustard oil with the film-forming property of chitosan, we studied the inhibition of pathogens, the rate of water losing and decay index of mustard oil and chitosan liquid in postharvest tangerine. Results showed that the antibacterial effect of compound liquid for the pathogenic bacteria of tangerine-penicillium digitatum was obvious, and the minimum bacteriostatic concentration of mustard oil on pathogens penicillium was 0.025μL/mL, and the minimum bactericidal concentration was 0.075μL/mL. By observing the changes of water loss rate and decay index of tangerine during storage, and carrying on the preliminary analysis:when the mustard oil concentration of compound liquid was 40⁸0μL/mL, the storage effect was clearly, better than that of natural condition.