The invention discloses an inverse-Y-shaped microflow selector valve for a Lab-on-CD disc and a sample separating method and belongs to the technical field of microfluid. The valve comprises a round cavity A provided with a ventilation hole, wherein a capillary valve communicated with the cavity body is arranged below the round cavity A, the capillary valve is communicated with a fluidic generator, the width of the fluidic generator is larger than that of a pipeline of the capillary valve, a Y-shaped microflow pipeline branch is communicated to the lower portion of the fluidic generator, and a round cavity B and a round cavity C provided with ventilation holes are connected to the two parts of the Y-shaped microflow pipeline branch respectively. The valve overcomes the influences of Euler force and coanda effect on fluid, and sample separation of any branch of a Y-shaped microflow pipeline capable of controlling the flow direction of liquid can be realized by means of Coriolis force generated through forward and reverse rotation of a Lab-on-CD centrifugal platform without any external force. The valve is simple in design, reasonable in structure and easy to realize.