The invention discloses epoxidized soybean oil resin-matrix rigid foam plastic and a method for preparing the same. The plastic is obtained by synthesizing compositions with the following weight portions: 100 portions of epoxidized soybean oil resin, 10 to 60 portions of vinyl monomers, 1 to 6 portions of vesicant, 1 to 4 portions of foam stabilizer, 4 to 10 portions of evocating agent, 2 to 6 portions of accelerant, 2 to 10 portions of water, and 0 to 20 portions of sisal fibers. The epoxidized soybean oil resin-matrix rigid foam plastic prepared by the invention has good performance, the density is between 0.1g/cm <3> and 0.3g/cm <3>, the compressive strength is between 300 and 3500kPa, the performance approaches that of the prior thermosetting rigid foam plastic, and the plastic can beused for building materials, furniture materials, heat insulating and sound-insulating materials and so on. Reinforced fiber and main matrix resin of the plastic both derive from renewable resources,so the plastic has full biodegradation performance and is an ideal substitute for treating 'white pollution'.