The in-flight calibration of large-field atmosphere sensors without the onboard calibration system using broad sea-non equipped sites (SNES) is a recommended method. Herein, based on the working principle of the Directional Polarimetric Camera (DPC) and the characteristics of its level-1 data products and the reflection base method, the simulation of sea surface bidirectional reflectance distribution function (BRDF) transfer to the top of the atmosphere is processed to determine the appropriate threshold angle to reduce nonatmospheric molecular scattering interference. At the same time, the statistical analysis of the calibration sites’ environmental parameters is analyzed to solve the data selection and incorrect budget problems. Finally, the accurate evaluation of the in-flight calibration coefficient changes of DPC at visible bands is achieved. The final calibration error of the absolute radiation calibration coefficient is between 1.24% and 4.76% subsequent to considering the calibration source and instrument laboratory calibration error synthesis.