Objective Gitelman Syndrome is a disease caused by the mutation of Na-Cl cotransporter gene(SLC12A3).The article studied the significance of diagnosis and identification by genetic mutation. Methods We collected the clinical data, then we sequenced the SLC12A3 gene by the first sequencing technology and MLPA. Results SLC12A3 complicated heterozygotic mutation was observed.One of them showed c.1964G>A, p.(Arg655His) and exon 8 deletion mutation, the other showed c.2543A>T, p.(Asp848Val) and c.976delG, p.(Val326fs) mutation of SLC12A3 gene in children. Conclusion The final diagnosis depended on gene diagnosis. Pediatrician must recognize the manifestations to advoid misdiagnosis.