Abstract: In the design of the radiography system, designers often need to calculate the system performance indexes. In order to improve the product development efficiency, Nuctech Company Limited and Tsinghua University have jointly developed a professional radiography simulation software NucRPD based on Geant4 for the first time in China. NucRPD has established the parameterized models for the often used radiography systems, so that users can simply modify a few parameters from the user interface to quickly build a virtual radiography system, including the geometry, the particle source, the physical processes and the statistical quantities. Then NucRPD can carry out the parallel calculations in the computing cluster to give the simulation results in a short period. NucRPD can also show the results in an intuitive and elegant way to help users to deeply understand the simulation results. We have compared the simulation results of NucRPD with a large set of experiments, and simulation results of the imaging performance and radiation protection performance agree well with those of experiments. NucRPD has been successfully applied to the designs of the radiography products in Nuctech Company Limited, and it has played an increasingly important role in optimizing the imaging performance and radiation protection performance.