The utility model relates to a control system of a low temperature liquid hydrocarbon evaporator, which comprises a second controller, a third controller, a No. 1 temperature sensor which detects the temperature of gaseous hydrocarbon, and a water vapor inflow valve which controls the flow of water vapor flowing into a vapor pipe, wherein the No. 1 temperature sensor is positioned on the pipeline of a hydrocarbon pipe for outputting the gaseous hydrocarbon, and is connected with the third controller for sending the temperature of the gaseous hydrocarbon to the third controller which is connected with the second controller, and sends a water vapor inflow increasing signal to the second controller when the temperature of the gaseous hydrocarbon is lower than a first temperature; the second controller is connected with the water vapor inflow valve, and sends the flow increasing signal of the vapor pipe to the water vapor inflow valve according to the water vapor inflow increasing signal; and the water vapor inflow valve is positioned on the pipeline of the vapor pipe from which the water vapor flows into, and is further opened under the control of the flow increasing signal of the vapor pipe. The control system of the low temperature liquid hydrocarbon evaporator can improve the operational efficiency and stability of the evaporator, gaseous hydrocarbon users can continuously and stably operates, and the energy is saved.