Abstract: To make clear the differences of optical path transmission and output signal between full-integrating sphere and semi-integrating sphere, the optical transmission models of the two integral spheres under fiber detection manner were established respectively. The formulas of output signal intensity and detection sensitivity were derived for the two kinds of integrating sphere tests. Based on the derived formulas, the theoretic analysis and verification experiments were conducted. It is found that both the signal intensity and the detection sensitivity for the two kinds of sphere tests depend on the coating reflectivity, the radius of integral sphere and the numerical aperture angle of optical fiber. Whether the semi-sphere performance is better than the fullsphere depends on the selection of the diffuse coating reflectivity and the mirror reflectivity. High reflectivity of mirror coating can improve the semiintegrating sphere sensitivity, while the low value can reduce the output. When the reflectivity of mirror coatings tends to 1, the output signal intensity of semisphere can be 2 times as the one of full-sphere.