The utility model relates to the technical field of insulators, in particular to a composite insulator capable of quickly replacing a core rod, which comprises a first shell, a second shell and the core rod, a plurality of umbrella skirts are arranged on the outer wall of the first shell, a first slot is arranged at the bottom of the first shell, a second slot is arranged at the top of the second shell, and the core rod is positioned in the first slot and the second slot. Two circular slots which are symmetrically distributed left and right are formed in the positions, close to the top end, of the outer wall of the second shell, a connecting sleeve is arranged at the bottom of the outer wall of the first shell, and a locking piece is arranged on the outer wall of the connecting sleeve. According to the composite insulator capable of rapidly replacing the core rod, through the linkage design of the spring and the pull rod of the locking piece, the locking state of the second shell can be rapidly released only by pulling the pull ring outwards, so that the core rod can be directly pulled out and replaced, and compared with the tedious operation of dismounting a rubber sleeve or fastening a bolt in the prior art, the operation is more convenient. According to the composite insulator, the maintenance time is greatly shortened, the maintenance can be completed without a professional tool, and the maintenance efficiency is remarkably improved.