The invention belongs to the technical field of electric power systems, and specifically relates to a micro-grid relay protection device and protection method. According to the device, each signal acquisition and identification system sequentially comprises a first switch, a sampling circuit, a second switch, a first retaining circuit, a third switch, a first branch circuit and a second branch circuit which are arranged in parallel, a subtraction operational circuit, an absolute value operational circuit, a voltage comparison circuit, a sixth switch and a controller according to an electric signal transmission direction, wherein the first branch circuit comprises a fourth switch and a second retaining circuit, and the second branch circuit comprises a fifth switch and a third retaining circuit; and the method comprises the following steps: controlling time sequences of each switch, monitoring total number of times and continuous number of times that input voltages are greater than threshold voltages in the voltage comparison circuit, and outputting tripping control signals. By adopting the micro-grid relay protection device and protection method disclosed by the invention, the switching between two modes can be achieved, and meanwhile, the timeliness of fast quick-break protection can also be achieved; the problem of missing switching signals can be avoided; and the problem of wrongly judging non-stable distorted noise signals of a grid as the switching signals can also be avoided.