We measure the effect of two-dimensional electron gas in ZnS0.06Se0.94/Zn0.8Cd0.2Se at low temperature and high magnetic field by SdH measurement. We find the energy gap of ZnS0.06Se0.94/Zn0.8Cd0.2Se When it tends toward 0K by PL measurement. Although we did not observe the persistent photo-conductivity effect in this experiment , it is especially that we can lower temperature at 0.03K. In the low temperature, we can observe more figures of SdH and acquire more exact information of electron concentration and effective mass in the future.