The invention provides a mold for a base of a junction box. The mold comprises a top plate, an upper heat insulation plate, an upper mold plate, a lower mold plate, a lower heat insulation plate, a bottom plate, a mold insert and a pressure block, wherein the upper heat insulation plate is arranged on the lower surface of the top plate; the upper mold plate is arranged on the lower surface of the upper heat insulation plate; the lower mold plate is arranged on the lower surface of the upper mold plate, and a mold cavity is defined between the upper mold plate and the lower mold plate; the lower heat insulation plate is arranged on the lower surface of the lower mold plate; the bottom plate is arranged on the lower surface of the lower heat insulation plate; the mold insert is arranged between the upper mold plate and the lower mold plate; the pressure block is arranged on the side surface of the mold insert and fixed on the upper mold plate through a fixing device, and an opening and closing device is arranged on the outer side of the pressure block. According to the mold provided by the invention, the influenced on the pressure block can be prevented by outwards adjusting the position of the opening and closing device, the damage frequency of the opening and closing device is lowered greatly, the pressure block is prevented from being stuck, the efficiency of disassembling and assembling the mold is improved, and further, the quality of the mold is improved.