The invention relates to a reciprocating type circulating single micro-channel device facing a fluorescent PCR (Polymerase Chain Reaction) micro-system and belongs to the detection fields of biology, analytical chemistry and medical science. The reciprocating type circulating single micro-channel device is characterized in that three temperature regions in PCR amplification are composed of metal pipes with good thermal performances; the three metal pipe temperature regions are connected by using ultraviolet laser cure optical colloids; the reciprocating type circulating single micro-channel device not only has the effects of isolating heat, sealing and supporting, but also has the light transmitting property; a mini-type fluorescent detection system can also be arranged to form a real-time fluorescent PCR microfluidic system. The reciprocating type circulating single micro-channel device has the essences that compressed air or silicone oil moves back and forth in a single micro-channel and a small section of a PCR reagent is used for finishing the PCR amplification of forty temperature cycles in the three temperature regions. Therefore, the volume and the weight are reduced, the reagent is saved and the reciprocating type circulating single micro-channel device is suitable for automatically working in a space on-orbit zero-gravity environment.