The invention discloses a disassembly-free cleaning agent for a fuel spray nozzle and belongs to the field of automobile engines. On the basis that the total mass of the cleaning agent is 100 percent, the disassembly-free cleaning agent for the fuel spray nozzle comprises the following components in percentage by mass: 5 to 22 percent of decarbonizer, 3 to 25 percent of accelerant, 10 to 25 percent of combustion improver and 40 to 80 percent of diluent. The disassembly-free cleaning agent for the fuel spray nozzle is prepared by uniformly mixing the decarbonizer, the accelerant, the combustion improver and the diluents at normal temperature and normal pressure. The cleaning agent can effectively clean deposit of the fuel spray nozzle, avoids deformation and swelling of plastic and rubber,is combusted completely, avoids engine knocking and does not corrode metal parts.