It is researched that the measuring methods of radiation imaging and temperature fields of red-hot castings. It can be gotten the contour lines of radiation illumination on castings' surface through comparing its values of three colors red, green and blue in computed graphs. It can be measured that the temperature fields of castings in the changing space and time, after marking the measuring system in the relationship between CCD camera, the values of RGB, black body systems, illumination and radiation temperature. It can be controlled the size of the new producing zones and densities of the contour lines to deal with the original graphs in computer, through adjusting the color ranks for first figured contour. So it is sticking out the main, blazing objects and can get the isothermal line from the isohypse. It is an useful tool to resupply the computer solidification simulation and analysis of casting defect. It has potential usage in the foundry engineering, for example, monitor, data of radiation and temperature in the procedure. It can also help to check the solidification simulation results and to provide the initial condition or boundary.