In order to calibrate the six apertures of a multi-angle polarizing radiometer synchronously and to meet the need of full beam path calibration. a six-hole ellipsoid integrating sphere calibration source was designed according to the optical characteristics and structural constraint of the polarizing radiometer. Then the consistency, uniformity and polarization of the integrating sphere output were tested. In the test, the consistency was directly measured by using the scaled spectral radiometer, while the uniformity was detected by using the scanning method combined a lens and apertures in consideration of the small outlet of the integrating sphere. Furthermore, the degree of polarization was detected by a linear polarization detector designed based on the Marius extinction law. Experiments demonstrate that the detection methods and data processing have enhanced the signal-to-noise ratio as well as the accuracy of the system. It is shown that the brightness consistency of paired openings for the integrating sphere is better than 99.5%, the surface uniformity is better than 99%, and the degree of polarization is below 1%, which satisfies the needs of radiometric calibration of the multi-angle polarizing radiometer.