Variation law of combustion performance of glass fiber reinforced epoxy composites under different heat fluxes was studied. Final result shows that the time of epoxy resin composite shortened when increased the heat flux, and the theoretical minimum ignition heat flux obtained by curve fitting of experiment data is 2.1638kW/m2; multiply heat flux increased the heat release rate and complicate the stratified combustion of materials, which making the heat release rate curves more complicated. What is more，multiply the heat flux caused incomplete combustion of materials and leaded greater smoke production rate. The residual quality decreased as increased heat flux, however when the heat flux beyond 50kW/m2, the residual quality no longer decreased, which suggested that the heat flux used to study these materials should not be more than 50kW/m2. To sum up the above combustion parameters ,we could know that the safety performance of this epoxy composite was medium level, in order to improve its security level further, smoke suppression should be handled.