The invention discloses a guiding sheathing canal, a 
catheter and an oval 
nest detection method for inter-atrial septal puncture. The guiding sheathing canal comprises a 
tail end sheathing canal and an adjustable bent section connected with the 
tail end sheathing canal, a first sheathing canal magnetic positioning sensor and a second sheathing canal magnetic positioning sensor are arranged at thetwo ends of the adjustable bent section respectively, the first sheathing canal magnetic positioning sensor is close to the 
tail end sheathing canal, and the distance between the end, close to the tail end sheathing canal, of the first sheathing canal magnetic positioning sensor and the free end of the tail end sheathing canal is remarked as L; the guiding sheathing canal is used for being matchedwith the 
catheter, the 
catheter can move in the axial direction of the guiding sheathing canal, the distance between the end, close to the tail end sheathing canal, of the first sheathing canal magnetic positioning sensor and the free end of the catheter is marked as D, and the free end of the catheter is provided with a 
pressure sensor and a catheter magnetic positioning sensor. According to theguiding sheathing canal, inter-atrial septal puncture is more accurate and effective, puncture time is saved, more importantly, zero 
ray in the puncture process can be achieved, the bodies of doctorsand patients are better protected against 
radiation influences, and the guiding sheathing canal is simple in structure, convenient to use and good in effect.