The utility model discloses a cold start -up system of excavator, characterized by, including battery, travel switch, first relay, coolant heater, second relay, firewood oil heater, electromagnetism valves, third relay. The utility model discloses cold start -up system of excavator passes through the setting of travel switch, first relay, second relay, third relay, and control cooling liquid heater heats diesel oil the heating of engine cooling liquid, control firewood oil heater before opening the car to do benefit to the start -up of excavator, after opening the car and finish, cut off resetswitch, first relay, second relay, third relay through travel switch, and then make coolant heater, firewood oil heater in work, practice thrift the energy.