A time relay suitable to be used in a metal halide lamp and similar loads, comprising a power side phase wire terminal, a power side neutral wire terminal, a load side live wire terminal, a load side ground wire terminal, and a control circuit, wherein the neutral wire terminal is connected with the ground wire terminal, an output contact of the relay is connected between the phase wire terminal L and the live wire terminal in series, wherein: the control circuit comprises a buck regulator rectifier circuit, an outage detection circuit, a timing control circuit, a tank circuit and a relay output circuit; two poles of an AC input end of the buck regulator rectifier circuit are respectively connected with the phase wire terminal and the neutral wire terminal, and loading voltage or unloading voltage at a direct current output end of the buck regulator rectifier circuit is controlled by electrification or outage of the phase wire terminal and the neutral wire terminal; wherein the buck regulator rectifier circuit is connected with the relay output circuit to supply electricity, a detection signal input end of the outage detection circuit is connected with a positive pole node of the direct current output end of the buck regulator rectifier circuit, an output end of the outage detection circuit is connected with a processing signal input end of the timing control circuit to provide a detection signal of loading voltage or unloading voltage of the positive pole node of the DC output end of the buck regulator rectifier circuit; an electric energy input end of the tank circuit is connected with a voltage regulating node and a voltage-stabilizing node of the direct current output end of the buck regulator rectifier circuit, an output end of the tank circuit is connected with a power input end of the timing control circuit, such that energy is stored when voltage is loaded at the direct current output end, and the electricity is supplied for the timing control circuit when the voltage is unloaded; and wherein a control signal output end of the timing control circuit is connected with a control signal input end of the relay output circuit, such that at the instant that the direct current output end is converted from loading into unloading voltage, the tank circuit is configured to supply electricity to the timing control circuit, the outage detection circuit is configured to output a voltage unloading signal to the timing control circuit, the timing control circuit is configured to enter a long time delay timekeeping process, and the situation that the output contact of the relay is prohibited to be closed until the timekeeping process is finished is controlled by the control circuit through the relay output circuit. the control circuit comprises a buck regulator rectifier circuit, an outage detection circuit, a timing control circuit, a tank circuit and a relay output circuit; two poles of an AC input end of the buck regulator rectifier circuit are respectively connected with the phase wire terminal and the neutral wire terminal, and loading voltage or unloading voltage at a direct current output end of the buck regulator rectifier circuit is controlled by electrification or outage of the phase wire terminal and the neutral wire terminal; wherein the buck regulator rectifier circuit is connected with the relay output circuit to supply electricity, a detection signal input end of the outage detection circuit is connected with a positive pole node of the direct current output end of the buck regulator rectifier circuit, an output end of the outage detection circuit is connected with a processing signal input end of the timing control circuit to provide a detection signal of loading voltage or unloading voltage of the positive pole node of the DC output end of the buck regulator rectifier circuit; an electric energy input end of the tank circuit is connected with a voltage regulating node and a voltage-stabilizing node of the direct current output end of the buck regulator rectifier circuit, an output end of the tank circuit is connected with a power input end of the timing control circuit, such that energy is stored when voltage is loaded at the direct current output end, and the electricity is supplied for the timing control circuit when the voltage is unloaded; and wherein a control signal output end of the timing control circuit is connected with a control signal input end of the relay output circuit, such that at the instant that the direct current output end is converted from loading into unloading voltage, the tank circuit is configured to supply electricity to the timing control circuit, the outage detection circuit is configured to output a voltage unloading signal to the timing control circuit, the timing control circuit is configured to enter a long time delay timekeeping process, and the situation that the output contact of the relay is prohibited to be closed until the timekeeping process is finished is controlled by the control circuit through the relay output circuit.