This is a study on serotypes 1-14 Ureaplasma urealyticum (Uu) infections of genitourinary in different populations. The results show that 1) the Uu infection rate is the highest in sexually promiscuous persons with STDs (78/115, 67.83%), lesser in both sexually promiscuous persons without STDs (97/185, 52.43%) and in general population with common genitourinary infections (84/180, 46.67%), and the lowest in healthy controls (73/320, 22.81%); 2) all of the 14 serotypes and untypeable Uu infections existed in China are identified; 3) the relationship between Uu 1 and 4 serotype and infections is stronger, but medium strong in 2, 8 and 10 serotype, whereas, 3, 9 and 14 serotype are major colonizational strains; 4) multi-serotypes infections are closely associated with sexually promiscuous behaviour.