In this work, plastic foams were prepared from plant oil resins based on soybean oil and castor oil. Firstly, epoxidized soybean oil (ESO) reacted with acrylic acid using N, N-dimethyl benzyl amine as the catalyst, and castor oil was modified with maleic anhydride, respectively. Acid number was used to monitor the reaction process, and structures of the resultant acrylated epoxidized soybean oil (AESO) and maleate castor oil (MACO) were proved by Fourier Transform Infrared (FTIR) measurements. It was found that the catalyst is quite effective in synthesizing AESO. Then, plastic foams based on AESO and MACO were synthesized through free radical initiated copolymerization with diluent monomers including styrene and methyl methacrylate. Mechanical properties, reinforcing effect of sisal fiber and biodegradable feature of the foams were characterized, showing the suitability of the bio-foams for acting as packaging materials.