Biodegradable poly(propylene carbonate) (PPC) was blended with o-lauroyl chitosan (OCS) by solution casting using chloroform as common solvent. FTIR and XPS confirmed hydrogen bonding interaction between PPC and OCS, which was saturated when OCS loading reached 20wt%. Because of the hydrogen bonding interaction, a 2–3°C increase in glass transition temperature and a 5% improvement (46–53°C) in weight loss temperature (T 5% ) were observed in the PPC/OCS blend with OCS loading of 10–20wt%. The interaction was beneficial to improving the mechanical performance of PPC. The tensile strength, elongation at break, and Young's modulus of the pure PPC film were 31MPa, 3.8%, and 392MPa, respectively. For the blend with 10wt% OCS loading, the effect of toughening was so substantial that the maximum elongation at break increased twofold to 8.1% and Young's modulus increased nearly threefold to 1014MPa; the tensile strength and stress at break remained unchanged.