Non-halogen flame retardant ABS was prepared by using epoxy resin and triphenyl phosphate (TPP) as flame retardants. The effects of the types of epoxy resin, component ratio and contents on the limited oxygen index (LOI) and mechanical properties of the flame retardant ABS were studied. It was found that novolac epoxy resin (NE) and TPP had excellent synergistic effects on the flame retardancy of ABS. When the mass ratio of NE and TPP was 1∶1 and the total content was 20%, the LOI value of the flame retardant ABS was as high as 41.5%, and the mechanical properties of the ABS was good. TGA results showed that NE could inhibit the volatilization of TPP, NE and TPP could delay the thermal degradation of ABS and increase the percentage of chars.