Pyelonephritis is an inflammation of the renal pelvis, mostly caused by bacterial infection, usually accompanied by inflammation of the lower urinary tract, which is not easily and strictly distinguishable in clinical practice. Patients with pyelonephritis, treated with effective antibiotics, will usually have significant improvement in symptoms within 2 to 3 days. If there is no improvement, symptoms worsen, and there is persistent high fever and significant increase in blood leukocytes, the emergence of complications should be considered. Common complications of pyelonephritis are: 1, complication of infectious stones: the composition of stones is mainly magnesium ammonium phosphate, which is due to the urease contained in Bacillus deformans and others, which can break down the urea in the urine, making the urea alkaline, while the solubility of phosphate in alkaline urine is significantly reduced, and easy to produce precipitation and the formation of magnesium ammonium phosphate and apatite stones. 2, perinephric abscess: direct expansion from severe pyelonephritis, accounting for 90%, the causative organisms are mostly gram-negative bacilli, with Escherichia coli common, mostly present in diabetes, urinary stones and other unfavorable factors, patients often have obvious unilateral lumbago and pressure pain, and the pain increases when bending to the healthy side. Treatment is appropriate to use powerful antimicrobial agents, strengthen supportive treatment, or incision and drainage. 3, gram-negative bacillus sepsis: mostly occurs in acute, severe pyelonephritis, the performance is dangerous, sudden chills, high fever, often cause shock, mortality rate of 50%, should be actively given strong antibacterial agents, strengthen supportive treatment. 4, renal papillary necrosis: is one of the serious complications, often occurs in patients with diabetes or urinary tract obstruction pyelonephritis, can be complicated by sepsis or lead to acute renal failure.