Abstract: objective:To investigate the melamine milk powder incident by ultrasound screening for kidney and ureter due to unexplained expansion of water,by multi-slice CT urography after inspection found water reasons,come to imaging diagnosis conclusion.Methods:Ultrasound screening of urinary tract stones were not defected,but the kidney and ureter due to unexplained expansion of water,all cases were done by multi-slice CT urography in imaging diagnosis was confirmed by surgery in 15 cases.Results:The multi-slice CT urography imaging diagnosis of 60 cases of congenital kidney and ureter in children is mainly caused by renal dysplasia and the side of renal agenesis and ectopia.Analysis of CT performance and multi-slice CT urography on the diagnosis of urinary tract abnormalities was 98.3% acurafe(59/60) and superior to IVP and ultrasound(p<0.05).Conclusion:Ultrasound examination should be used as a screening tool for congenital urinary system,but multi-slice CT urography of congenital urinary system is an important inspection method.Multi-slice CT urography is rapid,noninvasive,high resolution and combined with a variety of image processing technique,can be intuitive,three-dimensional display the whole process of the urinary system is the diagnosis of urinary congenital abnormalities of the ideal method with high clinical value.