Theoretically we have studied the current spin polarization in the structure of ferromagnetic/organic semiconductor under Schottky contact and discussed its variations with potential barrier height, the special carriers in organic semiconductor layer and the its mobilities, doping concentration near the interface. The calculations show that the high mobilities of the carriers in organic semiconductors are conducive to the spin injection. We also find that a significant depletion region at Schottky contact is highly undesirable for spin injection. For an efficient spin injection, the depletion region near the interface should be heavily doped and the effective barrier height should be restricted wichin certain range.