The utility model discloses a lightweight battery tray mold of a mold core reference positioning mechanism, which relates to the technical field of injection molds, and comprises a lower mold base and an upper mold base, the upper mold base is arranged at the top end of the lower mold base, a guide positioning mechanism is arranged on one side of the lower mold base, and the guide positioning mechanism is arranged on the other side of the lower mold base. According to the guide positioning mechanism, when the mold core body is installed, after a positioning pin is inserted into a positioning cavity, a bolt is screwed to drive a sliding rod to move, a limiting ball is pushed out of a clamping groove through an inclined face of a limiting groove and clamped into a fixing groove, and stable mechanical locking is formed; the position stability of the mold core under the injection molding pressure is effectively guaranteed, the limiting bead can be withdrawn by reversely rotating the bolt during disassembly, complex tools are not needed in the whole process, the replacement time of the mold core is greatly shortened, the mold maintenance efficiency is improved, meanwhile, high-precision reset of each time of installation is guaranteed, and the high-precision production requirement of the battery tray mold is met.