AbstractSafe and environmentally friendly oil-resistant packaging paper is strongly desired in the food packaging industry. In the present work, chitosan (CTS) and chitosan/cationic starch (CTS/CS) coated papers were prepared and characterized. The results indicated that both the CTS and CTS/CS coated papers were highly oil resistant, and their oil resistance was increased with an increase in coating weight. The CTS/CS composite showed better thermal stability and water resistance than CTS. Paper coated with the CTS/CS composite containing 1:2 CTS to CS achieved an oil resistance level as required for food packaging. The mechanism of CTS/CS oil resistance, which has not been reported, was investigated by SEM, HPLC and particle size analyzer. The high oil resistance of the CTS/CS-coated paper was attributed to the formation of a film on the surface of the paper and the electrostatic binding between CTS and fatty acid to prevent oil from permeating and transferring.