Objective To explore the effect of loading density of different rigid containers on wet package of orthopedic instruments in the department of orthopedics and to provide the basis for right loading of rigid container so as to ensure the success of the sterilization. Methods About 120 cases of orthopedic exotic instruments for knee surgery were selected from our hospital, according to size and weight of the knee surgery instrument and then evenly divided into Groups A, B, C, 40 pieces in each group. Each group for loading had the same length and width. In Group A, the loading was at 1/2 of the container height, in Group B, the loading was at 2/3 of the container height and in Group C the loading was 4/5 of the container height. The 3 groups were given high pressure steam sterilization, the sterilization temperature, sterilization time and drying time were the same, while biological and chemical monitoring was done. After sterilization, the three groups were compared in terms of the biological and chemical monitoring results as well as the incidence of wet pack. Results There were no significant differences between the 3 groups in the qualification rate of indicator cards and the biological monitoring after sterilization in the 5 kinds of packages among the 3 groups of rigid containers (P>0.05). The incidence of wet package in Group A was significantly lower than that of Group C (χ2=6.80, P=0.009<0.017), but no difference was found between Groups B and C ,Group B and C Group . Conclusions The loading density of different rigid containers affects the incidence of wet package of the orthopedic instruments. Our findings indicate that the loading of the instruments in a rigid container reaches the 2/3~4/5 height of the container, for it can reduce the incidence of wet package of orthopedic instruments.