Abstract: The solar is selected generally as a standard source on the on board solar calibrator of satellite multispectral sensors. The solar radiation is leaded into the space borne remote sensors and adjusted within the sensor's dynamic range by means of the solar calibrator. It is used to provide absolute radiometric calibration to the sensors and may be used to monitor and correct for possible performance changes of the sensors. Some solar calibrators used for space borne multispectral sensors are introduced and analysed, in order to reflect the present state and development of the solar calibration techniques.At present, the use of a solar diffuser is a desirable approach to the on board absolute radiometric calibration. It provides a full aperture, full field and end to end calibration. A serious drawback is that the diffuser's reflectance may change with time. In order to solve the problem a kind of ratioing radiometer or reflectance calibration assembly used to monitor the radiance and reflectance of the diffuser and solar constant is designed. Now the approach comes into use on some advanced space board multispectral sensors. The paper also puts forward some key techniques during the development of the solar diffuser after analyzing this aproach.