Based on the analysis of ferromagnetic mechanism of diluted magnetic semiconductors (DMSs), an Ising model with multi-exchange interactions is established. The reason of the shape of ferromagnetic order is simulated by Monte Carlo (MC) simulation with the Metropolis algorithm. The result reveals that the lower concentrations of Mn doping (x) are helpful for forming the ferromagnetic order. However, with the lower concentrations of Mn doping the magnetization of the system will be smaller and the Courier temperature will be lower. The modifying efect of carrier on the formation of ferromagnetism is enhanced with the increase of x and the decrease of the anisotropy constant (K). This work predicts that the increase of K will heighten the ferromagnetism and the Courier temperature.