The invention provides a micro-fluidic chip which is provided with a sample pond, a sample waste liquor pond, a buffer liquor pond, a buffer liquor waste liquor pond and a replenishing liquor pond, wherein the inlet of a separation channel communicates with the sample pond through a sample feeding channel, communicates with the buffer liquor pond through a buffer liquor channel, and communicates with the sample waste liquor pond through a sample waste liquor channel, respectively; the outlet of the separation channel communicates with a replenishing liquor pond with an injection pump through a replenishing liquor channel and communicates with the buffer liquor waste liquor pond through a buffer liquor waste liquor channel, respectively; the separation channel is formed by at least two same micro-channels which are connected in series; the micro-channels have bends, the micro-channels from the inlet to the bended sections are parallel one another, the micro-channels from the bends to the outlet section are gathered toward the center and communicate with the replenishing liquor channel and the buffer liquor waste liquor channel at the outlet, and porous plugs are arranged in the micro-channels and the buffer liquor waste liquor channels. The micro-fluidic chip provided by the invention for separating and detecting samples has the characteristics of being high in separation efficiency, high in detection sensitivity, simple in structure, convenient to operate and low in cost.