Abstract: With the development of quantitative remote sensing，interest in the radiometric calibration aspects of terrestrial remote sensing has been on the rise，and significant resources are being devoted to the relevant areas of research and development. The radiometric calibration of those sensors is a contributing factor to the success of application of remote sensing data. The calibration of sensors has relied on the preflight laboratory work as well as on in-flight techniques. At present，three kinds of in-flight radiometric calibration methods have been developed and widely used，namely，on-board calibration，in-situ calibration and cross-calibration. On-board calibrators，such as solar diffuser （SD） and solar diffuser stability monitor （SDSM），can be used for operational calibration；however，some satellites are not equipped with these due to power，weight，and space restrictions. In order to compensate for the limitations of on-board calibration systems，many methods have been proposed and used for in-flight radiometric calibration，such as in-situ calibration and cross-calibration. The problem with in-situ calibration is that it could be labor intensive，costly and time consuming．This typically limits the number of calibrations that can be performed. Cross-calibration is an alternative and potentially easier technique that can be used to acquire post-launch calibration coefficients. In comparison to in-situ calibration，cross-calibration can circumvent the strict requirements of atmospheric and surface variables；it is a cost-effective and convenient mean of calibration without the need of accurate synchronous in-situ measurements，compensating for the deficiencies of in-situ calibration. To date，many cross-calibration methods have been proposed with the same goal but different application conditions，advantages and limitations. Therefore，this paper aims to review these cross-calibration methods and to provide technical assistance for in-flight calibration. This paper gives descriptions of four cross-calibration methods，namely，ray-matching method，spectrum-matching method，radiative transfer modeling method and rayleigh scattering method. Besides，the advantages and drawbacks of these methods are also discussed in this paper. In practice，we can select the optimal cross-calibration methods in consideration of the scopes in these methods and the available datasets，promoting the development of quantitative remote sensing．

Key words: cross-calibration, ray-matching, spectrum-matching, radiative transfer modeling, rayleigh scattering