The difference between absorption of unfractionated heparin (UFH) and low molecular weight heparin (LMWH) after oral and oral cavity administration were studied respectively, and the compatible enhancer for oral cavity delivery system of both drugs was found.  The LMWH and UFH films were prepared with  two bioadhesive materials Carbopol and alginate sodium for oral cavity delivery.  The activated partial  thromboplastin time (APTT) was used to determine LMWH and UFH in plasma after oral, oral cavity and  sc administration in rats.  The results show that the enhancer (Labrasol) can increase the absorption of LMWH and UFH through oral cavity in rats but not obviously.  The oral cavity iontophoretic delivery system is a useful method to improve the absorption of LMWH and UFH through oral cavity mucosa.