Abstract: OBJECTIVE To apply the evidence-based thinking method in the monitoring of sterilization and explore the influencing factors for color changing of chemical indicator cards inside the sterilization packages so as to provide guidance for selection of appropriate chemical indicator card. METHODS The three categories of bags, including 5 kg surgical dressing bag, 7 kg surgical instrument bag, and 8 kg surgical dressing bag, were sep up, then the 132 ℃ steam sterilization chemical indicator card (card A), 1322 IY(card B),and crawl type card (card C) were selected, the three kinds of chemical indicator cards were placed in the middle of each bag which was placed at the same part of sterilizer, and the results of monitoring of the three chemical indicator cards and the total qualified rate of monitoring were observed and compared among the three categories of surgical dressing bags. RESULTS There was no significant difference in the result of monitoring among the three categories of cards in the 5 kg surgical dressing bag; there was significant difference in the result of monitoring among the three categories of cards in the 7 kg surgical instrument bag and the 8 kg surgical dressing bag (P＜0.05).There was significant difference in the total qualified rate of monitoring of the three categories of cards among the 5 g surgical dressing bag and the 7 kg surgical instrument bag and the 8 kg surgical dressing bag (P＜0.05). CONCLUSION The accuracy of monitoring of the modified class 4 chemical card is the same as that of the class 5 card.It is necessary to choose appropriate chemical indicator card, avoid the monitoring errors, rigidly conform to operation procedures, and ensure the quality of the sterilization items.