The invention relates to the technical field of semiconductor processing equipment, in particular to a furnace door body structure for a diffusion furnace. The furnace door body structure comprises afurnace door body and a furnace door driving mechanism. The furnace door body comprises a door supporting plate, a furnace door supporting shaft, a limiting rotary shaft, a radial knuckle bearing, analuminum door, a connecting plate and a quartz door. The furnace door driving mechanism comprises a bottom plate, two sliding bar assemblies, a supporting plate, a rodless cylinder, a sliding rail assembly, a furnace door connecting rod, a first cylinder, a second cylinder, a first cylinder connecting block, a second cylinder connecting block, a first limiting block, two first limiting switches, asecond limiting block and two second limiting switches. The furnace door structure body structure provided by the invention is simple in structure and good in sealing performance. The furnace door driving mechanism is smaller in occupied space and accurate in travel control. When the diffusion furnace adopts the furnace door body structure, the sealing performance of the furnace door body can meet the process requirements. The furnace door body as a whole does not need to be integrated with a boat feeding mechanism and is convenient to install and maintain, and the production efficiency is greatly improved.