The present invention relates to a noise elimination and electricity saving vector type leakage detection method and a leakage protector belonging to the power system leakage detection field. A zero-order current transformator is used to detect the leakage vector and residual current of low voltage distribution line to ground. The I delta p calculated through vector is real mutation leakage current value occurred on power supply line. If the current value is greater than the set value, an interface PB4 of a singlechip IC2I/O outputs low pwl, a computation amplifier IC1/A outputs low pwl and a dynatrons T1 and T2 is cut off. The relays J1 and J2 break off, an alternative contactor KM is cut off and the low voltage distribution line stop supplying power. The leakage protector according to the detection method realizes no action dead zone; the output circuit adopts noise elimination and electricity saving circuit, thereby having obvious energy saving effect; an isolating protection circuit is added between the I/O interface of the singlechip and the noise elimination and electricity saving output circuit, thereby prolonging the life-span of products.