The invention provides a New Jersey guard bar structure convenient to disassemble and a construction method. The New Jersey guard bar structure comprises a precast box beam and a guard bar rebar skeleton. The construction method comprises the steps that construction are arranged; measuring and setting-out are conducted; pre-embedded rebars arrangement is conducted; a sulphur mortar area is poured;rebars are machined and mounted; templates are mounted; concrete is poured; template disassembling and curing are conducted; a mortar protection layer is poured; blocks are connected; and when disassembling is conducted, firstly, a mortar protection layer is crushed, then the sulphur mortar area and the guard bar rebar skeleton are cut off, after nuts among the blocks, steel fasteners and pre-embedded screw rods on the top surface are disassembled, the blocks are hung away one by one, tools are picked up, and field is cleaned.According to the New Jersey guard bar structure convenient to disassemble and the construction method, the technology is reasonable, construction of the New Jersey guard bar with a cast-in-situ structure is simple, in the premise of not reducing the protection effectof the guard bar, the New Jersey guard bar structure convenient to disassemble is adopted, use of large-scale disassembling equipment is avoided, disassembling difficulty is lowered, fast disassembling of the cast-in-situ guard bar is achieved, thus the disassembling efficiency is improved, meanwhile the condition of concrete crushed-block splashing is reduced, and traffic safety is not influenced.