Visible calibration is one of the key technologies for multi-channel scan radiometer (MCSR) on FY-2 geostationary meteorological satellite. Accurate pre-launch calibration is the base and foundation for applications of meteorological information. According to the Beer principle, a set of technique and process fit for FY-2 MCSR are provided and set up to accomplish the outfield visible calibration in Kunming. We also analyze the error and tolerance sources to substantiate and improve our experiment data, which validates that all results are credible and satisfied.