Objective To investigate the diagnostic values of vitamin D deficiency rickets,including serum 25-(OH)D₃,bone alkalinity phosphatase(BALP),total calcium and so on. Methods A total of 1 190 children were tested and investigated aged 0~4 years old.Part of them were randomly selected to check BALP,25-(OH)D₃,total calcium,phosphorus,alkalinity phosphatase,bone mineral density(BMD) and taken X-ray. Results Serum 25-(OH)D₃ in rickets was significantly lower than the control group,the area of 25-(OH)D₃'s ROC curve is 0.633 (95%CI:0.581~0.684) which was moderate diagnostic.For Xichang crowd,the most appropriate concentration for cutoff point of diagnosing Vitamin D Deficiency is 72.86 nmol/L.Using this cutoff point to diagnose rickets,the sensitivity is 65.35%,and the specificity is 56.02%.Bone density,calcium,phosphorus,alkaline phosphatase,bone alkaline phosphatase can be used as indicators of a variety of inspection rickets secondary screening tool,as their diagnostic are weak.Combine 25-(OH) D₃ and bone alkaline phosphatase to diagnosis early and active phase rickets,the sensitivity increased to 76.67%,and specificity increased to 90.91%.Conclusion Serum 25-(OH)D₃ concentration is a good index for Rickets diagnosis.BALP is more sensitive and specific,which can be used for Vitamin D Deficiency Rickets screen.It clearly indicates we can diagnose better when we combined BALP and 25-(OH)D₃`s results,especially recognizing more patients in their early period or active period.