To discuss bacteria of urine infection reoccurrence , the routine culture and L-form bacteria culture of urine tract infection on 850 cases were adopted and clinica l watching and analysis of the bacteria plasmid were held ．Result: of the l28 cases, re-infec tion rate l5.0%．,the positive rate of the routine bacteria culture for those initial diagnosis patie nts was 58.3% while that of the re-infection patients was 34.0% P<0.0l ．The initia l diagnosis L-form inspected rate 5.6%yet that of re-infection was up to 32.0 % P<0.01 ．The analysis of the pla smid bacteria of re- infection were of the same origins ．Conclusion: the first infection dont nee d L-form culture but re- infection should have L-form culture ．Analysis: plasmid positive bacteria of r e-infection was the result of the first infection not completely cured．