In order to conduct nuclear analyses for Chinese Fusion Engineering Testing Reactor (CFETR) according to the latest design, it is necessary to establish a 3D neutronics model based on the engineering CAD model. The 360-degree CFETR engineering CAD model is an extremely complex and huge model, with a large number of spline surfaces, flow channels, and overlaps, which puts forward higher requirements for the modeling and the conversion code. In this paper, the detailed modeling and conversion process is introduced, and a detailed 3D neutronics model for 360-degree CFETR is created by cosVMPT (Visual Modeling Platform for Particle Transport). Furthermore, considering the update and maintenance of the CAD model in the future, a new function of “User-Defined-Void” is developed in cosVMPT. The converted geometry is validated by comparing results of volume calculations by MCNP and CAD system. The result shows that the generated three-dimensional neutronics model is in good agreement with the original CAD model. This study demonstrates the capability of cosVMPT to be applied to the nuclear device with large scale complex geometry.