Relating to the field of organic glass materials, the invention discloses an organic glass material and a preparation method thereof. The material comprises the following raw materials: polymethyl methacrylate, modified waste glass slag, aluminum oxide, highly dispersed white carbon black, glass fiber, N-hydroxymethyl acrylamide, polyhexanediol adipate, an ethoxylated compound, pyromellitic dianhydride, dimethyl sulfoxide, polydimethylsiloxane, an expansion agent, a clarifying agent, an initiating agent and a plasticizer. The preparation method includes: raw material mixing, heating and reaction. The organic glass material provided by the invention is simple and convenient to prepare, and has the characteristics of high flexural and compressive strength, good impact toughness, good machining properties, high temperature resistance and chemical reagent corrosion resistance, greatly widens the application fields of the organic glass material, prolongs the service life of organic glass products and improves the practicability of organic glass products, and has broad market prospects.