A series of polyurethane elastomer with varying proportion of polydimethylsiloxane were synthesized based on isophorone diisocyanate, isophorone diamineas as the hard segments and polytetrahydrofuran glycol, polydimethylsiloxaneas as the soft segments. The polymers morphology and microphase separation of the series of polyurethane were investigated by fourier transfer infrared spectroscopy, X-ray diffraction and differential scaning calorimetry. The results show that phase separation increases with increasing of PDMS. The molecular weight, mechanical and surface property of the polyurethane with different PDMS contents were studied by gel permeation chromatography, tensile test and contact angle test. The results show that the mecular weight and tensile strength decrease with increasing of PDMS, and the surface contact angle increases with increasing of PDMS. When the content of PDMS increases from 0 to 25%, the tensile strength decreases from 7.57 MPa to 0.64 MPa and the surface contact angle increases from 72°to above 95°.