The invention relates to a modified PVC wallboard and a production method thereof. The modified PVC wallboard is produced from, by weight, 45-55 parts of PVC resin, 8-20 parts of wood powder, 5-15 parts of calcium carbonate powder, 4.5-11 parts of a first assistant and 2.5-6.5 parts of a second assistant, wherein the second assistant comprises a modified AC foaming agent and sodium bicarbonate according to a mass ratio of (1.8-2.2):1, and the modified AC foaming agent comprises a calcium and zinc stabilizer, a rare earth composite salt stabilizer, barium stearate and an AC foaming agent according to a mass ratio of (1-2):(1-2):(1-2):(1-2). The modified PVC wallboard has excellent performances, and has better tensile property, impact property, bending strength and bearing capacity than present commercial products.