The invention discloses a nucleic acid extraction and amplification test tube and its working method, which belong to the field of molecular diagnosis and detection instruments, and its design points include: a PCR reaction tube, a lower tube of an extraction tube assembly, a middle tube of an extraction tube assembly, and an extraction tube assembly Upper tube assembly, top cover, piston rod, piston ring, first spool, second spring, second spool, third spring; extraction tube assembly upper tube assembly, extraction tube assembly middle tube, extraction tube assembly lower tube, The PCR reaction tubes are connected sequentially from top to bottom; the extraction tube assembly The upper tube assembly includes: two vertical parallel tube bodies: an extraction tube and a piston tube; a top cover is arranged on the top of the extraction tube; the piston rod is placed in the piston tube. The invention aims to provide a nucleic acid extraction and amplification test tube and its working method, which greatly improves the detection efficiency.