The present invention discloses a low-temperature heating system for a diesel engine. The system comprises an engine, a fuel heater, an electromagnetic valve, a coolant leakage alarm, a distribution control valve block, a temperature sensing directional valve, an oil tank heating device, and a pipe heating device. A first stop valve and a second stop valve are disposed on the fuel heater. A water outlet of the engine is divided into two passages with one being connected to the first stop valve and the other one being connected to a first water inlet of the distribution control valve block by means of the electromagnetic valve. The oil tank heating device is provided with the temperature sensing directional valve that has a control end connected with a temperature sensor. A first water outlet of the distribution control valve is connected to a temperature sensing directional valve of the oil tank heating device by means of the coolant leakage alarm. The pipe heating device is connected to an engine filter and an oil pump. The low-temperature heating system for a diesel engine effectively improves the viscosity and flowability of diesel oil at a low temperature to allow for sufficient combustion of the diesel oil, thereby ensuring that the diesel engine is started successfully and operates normally with achieved cost reduction and environmental protection.