The formation mechanism of urinary stones is complex and involves many genetic and environmental factors. The purpose of this study was to investigate the structure of MMP-7 protein and its role in the formation of urinary calculi, and to analyze the influence of PTH gene polymorphism on the clinical treatment of urinary calculi. The specific region of PTH gene was amplified by PCR (polymerase chain reaction), and the gene polymorphism was detected by restriction fragment length polymorphism analysis (RFLP). Then Western blot was used to detect the difference in the expression of MMP-7 protein between patients with urinary tract stones and healthy controls. The serum calcium concentration was determined by biochemical analysis and its correlation with the expression of MMP-7 protein was analyzed. The results show that there are specific PTH gene polymorphisms in patients with urinary calculi, and this polymorphism is significantly related to the susceptibility of urinary calculi. In terms of MMP-7 protein expression, patients with urinary tract stones showed significantly higher levels of MMP-7 protein than healthy controls. Further analysis showed that the high expression of MMP-7 protein was closely related to the increase of serum calcium concentration.