We synthesized polydimethylsiloxane-polyurethane dispersions modified with graft copolymerization (PDMS-G-PUDs) and polydimethylsiloxane-polyurethane dispersions modified with block copolymerization (PDMS-B-PUDs). We systematically investigated the effects of PDMS's structure, content, and molecular weight on properties of copolymer including viscosity, particle size, and stability of dispersions as well as the properties of the film formed by dispersions including gloss, contact angle, water resistance, oil resistance, and mechanical properties. The results demonstrated that the viscosity, particle size, water resistance increased but gloss decreased with the increase of PDMS content and molecular weight. In addition, we compared the properties of PDMS-B-PUD films and PDMS-G-PUD films with the same amount of PDMS and similar molecular weight. PDMS-G-PUD films showed higher water and oil resistance, but lower gloss and poorer mechanical properties. Scanning electron microscopy-energy dispersive spectroscopy analysis (SEM-EDS) indicated that the films of PDMS-G-PUD had better microphase separation and PDMS surface enrichment.