Objective: To explore gene diagnosis of autosomal dominant polycystic kidney disease (ADPKDⅠ) and to look for the typical mutation to improve the gene diagnosis. Methods: Southern blot and PCR was used to observe the mutation condition of 3′end single copy region of ADPKDⅠ gene; Amplifing and analysing the microsatellite SM7 by PCR. Results: (1) After the probe AH4 was hybridized with 16 patients′ genomic DNA by Southern blot, the common 15 kb fragments were found in every one; (2) For 27 patients, 5.72 kb genomic DNA, which is between the probe AH4 and JH14, was amplified by PCR, and no 5. 5 kb genomic DNA deletion were found in this region; SM7 was amplified in 109 health persons, its PIC was 0.76, and was closely linked with ADPKD Ⅰ gene in 3 patients′ family. Conclusion:(1) No large genomic DNA segment deletion can be found frequently in ADPKD Ⅰ gene 3′end single copy region; (2) The PIC of SM7 is high, it can be used to make rapid gene diagnosis in about 70%？80%ADPKDⅠfamily.