Because of the nonlinear response of FY-3C MERSI reflective bands , traditional calibration based on two-points is inapplicable. An integrated method for on-obit wide dynamic vicarious calibration is developed to resolve this problem. By combining various vicarious calibration methods which are independent on the ground synchronous measurement, and using the multi-scale reflectance characteristics of every program’s calibration sample, the integrated method can achieve wide dynamic radiometric calibration. Calibration samples from each program are integrated equally and weightedly by subsection-average method, and calibration coefficients are calculated based on integrated samples using weighted fitting regression. The prelaunch quadratic term of calibration experiment analysis is used to perform nonlinear correction, calibration slope and intercept are evaluated on-orbit. Anlysis and verification results show that sample distribution of each vicarious program shows well consistency and the correlation of integrated samples can reach 0.99. Regression residual of comprehensive calibration results is less than 1% for the medium to high dynamic with reflectance greater than 10%. The relative difference between the high-end calibration results with cross calivration based on deep convective clouds (DCC) test sample is less than 1.5%and Dunhuang simultaneous observation test results show that the medium accuracy is better than 3%. Because of the responsiveness to low-light radiance of MERSI shows large degradation, nonlinear coefficients acquired form prelaunch outside calibration experiment are inapplicable, and calibration results show over estimated at the low target reflectance. The results can be applied to all reflection channels of FY-3C MERSI, which can reduce the uncertainty of the two-points calibration and the influence of nonlinearity.