In order to prevent the microorganism of bulk roast chicken from exceeding the standard， it is necessary to identify its dominant microbes and inhibit its growth and reproduction. The main spoilage microorganisms were isolated and purified from roast chicken， and their morphology and physicochemical properties were determined. Propolis， water-soluble chitosan， nisin， sodium lactate and natamycin were used to inhibit the spoilage microbes. Four kinds of natural preservatives were screened out and used for preservation of roast chicken. The results showed that Bacillus subtilis and Bacillus pumilus were the dominant bacteria and Aspergillus candidus was the dominant fungus causing deterioration of roast chicken. The quality guarantee period of the total number of colonies could be prolonged by 4 folds when roast chicken were dipped by 0.3% propolis， 1% chitosan and 0.035% nisin during shelf life at 36 ℃， respectively. Adding 0.015% natamycin could also delay the emergence of mold for 2 days. The optimum combination of preservative for roast chicken was propolis 0.3%， water-soluble chitosan 0.4%， nisin 0.03% and natamycin 0.02%. The total number of colonies in non-packaged roast chicken did not exceed the standard within 60 h， and the shelf life of the treatment group was 5 folds longer than that of the control group. Therefore， the natural product preservatives allowing use in the food additives of national standard can be compounded to prevent the microbial spoilage of bulk roast chicken during the shelf life in summer.