Abstract: In order to solve the problems of high dependence on the import of insulating wood pulp and the shortage of high-quality wood fiber resources in China, and to realize the independent production of insulating paper for high voltage bushing, we studied the electrothermal multi-physical properties of bamboo paper and its epoxy composites. Firstly, the bamboo pulp was purified by adding hydrochloric acid and magnesium acetate in turn, and the effect of the purification treatment on the physicochemical properties of the bamboo paper was studied. Then, epoxy/bamboo paper composites were prepared, and their electrothermal properties were measured and compared with the insulating wood paper. The results show that the purification treatment can reduce the ash content of bamboo paper, enhance the bonding force between fibers, and improve the insulation properties and mechanical properties of the paper. The purification process of hydrochloric acid combined with magnesium salt can further reduce the electrical conductivity of the pulp extract and effectively reduce the dielectric loss. Purification treatment can effectively improve the glass transition temperature, dielectric properties, and breakdown strength of epoxy/bamboo paper composites, and enable their electrothermal properties close to or even better than the insulating wood paper. The results provide methods and ways to implement the carbon peaking and carbon neutrality goals and promote the independent research and development of electrical engineering basic materials in China.