The electronic properties of the solar cells were greatly influenced by the aluminum atomic concentration in Al-BSF region under that the Al-BSF is doped heavily. The effects of the dopincg profile in heavily-doped Al-BSF on electronic properties of n+pp+ monocrystalline solar cells were investigated by PC1D. The results show that the electronic properties of solar cells are almost independent of the doping profile of the Al-BSF, but are more or less affected by the BSF profile if the solar cell back surface is passivated well with the BSRV less than ~105cm/s. When the sheet resistance is about between 5 and 30Ω/□, the conversion efficiency can reach the maximum value. And the optimum thickness of Al-BSF is about between 10~15μm.