Abstract: The paper describes a novel instrument which can measure radiation coefficient of protective fabrics under high convective and radiant heat flux.It takes into account the effect of the coupled convective and radiant heat transfer, adopts a numerical analytical method to calculate convective heat flux,and establishes a systematic measurement and control platform based on virtual test technology.In particular,the problem of uncertainty of the convective heat transfer coefficient influenced by the coupled convective and radiant heat flux in a closed space is solved.The experimental results prove that the new tester can meet actual requirements and that it performs better than other instruments of the same kind.It is especially suitable for measuring radiation coefficient of protective fabrics when exposed to convective and radiant heat.