Abstract: In recent years, with the growing accuracy of observational requirement of remote sensing satellites, the proton shielding effectiveness of conventional materials is limited. It is difficult to shield high-energy protons by using only a single material. The radiation effect caused by space proton will lead to degradation or failure of optoelectronic devices of remote sensing satellites. Therefore, researchers have actively explored new and efficient proton shielding materials. Polyethylene (PE), a polymer material with a high hydrogen content, has better proton shielding performance compared with aluminum (Al) at the same mass thickness. Carbon nanotube (CNT) has unique electrical and mechanical properties, and thus, polymers doping with CNTs can significantly improve the physical properties of composite materials. In this paper, new proton shielding materials doping with CNT arrays (named PE/CNT) were designed on the basis of the PE material. The Geant4 simulation software was used to simulate the space proton shielding effectiveness of PE/CNT composite material. The PE/CNT composite material model was first constructed by considering some typical doping parameters including CNT doping concentration, diameter, arrangement mode, and layer number. Furthermore, the effects of these doping parameters on the proton shielding effectiveness of PE/CNT composite material were investigated. Afterwards, based on the above results, the ionization dose of space proton of PE/CNT composite material was evaluated and compared with PE. The results show three facts as follows. 1) the proton shielding effectiveness of the PE/CNT composite material is sensitive to the doping concentration, diameter, and arrangement mode, but less affected by the layer number. 2) PE/CNT composite material has superior proton shielding effectiveness in the case of a higher doping concentration of 20%, a bigger diameter of 5 nm, and a regular arrangement angle of 0° or 90°. It is obvious that the CNT arrays with irregular arrangement will have large gaps in the PE material, resulting in a decrease in the probability of collision between proton and CNT, and thus the proton shielding performance is inferior to the regular arrangement. 3) Under the same mass thickness, the ionization doses of the composite materials with doping CNT concentrations of 10% and 20% in the detector are reduced by 7.40% and 12.83% compared with the pure PE, indicating that the composite material exhibits better proton shielding effectiveness. It can be seen from the above three facts that PE/CNT composite material can be used as qualified proton shielding materials. The results of this study provide data support for the subsequent design of radiation protection materials.