A fluid particle-separating device includes a sorting, first and second diverting channels, a detector, a microprocessor, first and second actuators, and first and second sieving valves. The sorting channel receives fluid containing first and second particles. The first and second diverting channels guide the first and second particles. The detector recognizes the sizes and numbers of the first and second particles and outputs first and second recognition signals. The microprocessor receives the first and second recognition signals and outputs first and second control signals. The first and second sieving valves respectively inside the first and second diverting channels allow the particles to pass through or not. The first actuator receives the first control signal and controls the deformation of the second sieving valve to block the first particle. The second actuator receives the second control signal and controls the deformation of the first sieving valve to block the second particle.