Abstract: In order to use high ultraviolet light intensity more reasonably, by conducting fluorescent magnetic powder test(MPT) experiments, the relationship of ultraviolet light intensity to white light intensity was deduced and showed in the u-v curve, and by linear approximation to the u-v curve, the corresponding formula was acquired to describe the relationship. The research conclusion was proved to be scientific in a large amount of local tests, which filled a blank in fluorescent MPT technique.