The membrane system, photosynthetic system and antioxidant enzyme system of Racomitrium japonicum and Rhytidiadelphus squarrosus were characterized under stimulated stress environment of mixed heavy metal (Zn2+, Cu2+, Pb2+ and Cd2+) resolution in this study. The moss samples used in the study were collected from Wudalianchi, Heilongjiang Province. The compound heavy metal mixture was composed of the equal concentrations of four kinds of metal ions, such as Cu2+, Zn2+, Pb2+ and Cd2+. In this study, the samples were cultured in light incubators at 25 ℃ for 72 h, with a light cycle of 12 h: 12 h treated with six different metal concentration, namely 0 (control), 10, 30, 50, 60, 70 (μmol?L-1 of each kind of metal ions), respectively. The results showed that the content of free proline decreased first then increased and decreased again with the increasing concentration of compound heavy metal. The accumulation of proline in Rhytidiadelphus squarrosus under the metal concentration of 30 μmol?L-1 reached the maximum, which was 35.3% higher than that of the control; the maximum content appeared in Racomitrium japonicum under the concentration of 50 μmol?L-1 metal ions, which was 43.5% higher than that of the corresponding control. The above results implied the two concentrations of mixture ions were physiological limit of the two mosses. With the concentration of mixture metal ions increasing, MDA levels of Racomitrium japonicum and Rhytidiadelphus squarrosus also gradually increased, and reached the highest at 70 μmol?L-1, which were higher 66.7 ％ and 75.6 ％ than that of the corresponding control, respectively. The activity of SOD in two mosses increased first and then decreased. The highest levels of SOD activity of Racomitrium japonicum and Rhytidiadelphus squarrosus appeared under the ions concentration of 50 μmol?L-1 and 30 μmol?L-1, which were higher 15.7% and 28.8% than that of the corresponding control, respectively. The highest levels of POD activity of Racomitrium japonicum and Rhytidiadelphus squarrosus appeared under the ions concentration of 50 μmol?L-1 and 30 μmol?L-1, which were 80.1% and 98.1% higher than that of the corresponding control, respectively. Moreover, the lowest levels of POD activity in Racomitrium japonicum and Rhytidiadelphus squarrosus appeared at 70 μmol?L-1, which was 34.2% and 74.3% lower than that of the corresponding control, respectively. The trend of CAT activity was the same as that of SOD and POD. The highest levels of CAT activity in Racomitrium japonicum and Rhytidiadelphus squarrosus appeared under the concentration of 50 μmol?L-1 and 30μmol?L-1, which was 19.33% and 28.51% higher than that of the corresponding control, respectively. The maximum contents of soluble protein in Racomitrium japonicum and Rhytidiadelphus squarrosus appeared at the concentration of 30 μmol?L-1 and 10 μmol?L-1, which was 20.69% and 39.8% higher than that of the corresponding control, respectively. Along with the increase of metal concentrations, the chlorophyll content decreased, which implied that chlorophyll content of two kinds of mosses and metal ion concentration was significantly negatively correlated. The minimum chlorophyll content of Racomitrium japonicum and Rhytidiadelphus squarrosus appeared at 70 μmol?L-1, which was 62.5% and 67.0% lower that that of the corresponding control, respectively. Comprehensive analysis shows that Rhytidiadelphus squarrosus is more sensitive to heavy metal stress and could be an indicator to heavy metal pollution．