In this paper, bhe relative gpectral sensitivity distributions [S(λ)r] of photoelectric detectors are classified and compared. On the basis of above considerations, a new method for measuring S(λ)r using the pyroeleotrio detecbor as the reference and the integrating sphere as the monoohromatio radiation receiver has been suggested and designed. Because of the advantages of system structure, guch error factors as polarization and nonuniformity of incident radiation, temperature drift of detectors and stray radiation are decreased significantly.