The characteristic parameters,such as calibration sensitivity,dynamic range,modified quantity of radiating temperatures of radiometer's reference load and calibration blackbody of a new 3mm band radiometer,were measured.Due to the restriction of 3mm band technology in our country,there are many difficulties for designing and measuring a 3mm band radiometer.In this study,an aperture calibration technology was adopted to measure these characteristic parameters of this 3mm band radiometer by experiments.