Abstract: OBJECTIVE To probe into and analyze the effect of Ureaplasma urealyticum infections in genital tract on semen quality in male infertile patients. METHODS A total of 168 male infertility patients from Aug. 2016 to Mar. 2017 were selected in the hospital as infertile group. During the same time, 150 adult male volunteer were selected as fertile group. The U. urealyticum infection situation between the two groups, the physiological parameters of semen parameters, sperm motility and α-glucosidase levels in U. urealyticum infected and non-infected male infertility patients were compared and analyzed. RESULTS The U. urealyticum infection rate in genital tract of the patients in infertile group was 35.12%, which was significantly higher than that in fertile group (P＜0.05). Compared with U. urealyticum negative patients, in the patients with U. urealyticum positive, the sperm motility was (85.58±9.74) × 10⁶/mL, sperm viability was (45.74±5.22)% and sperm motility was (39.55±4.36)%, there were decreased significantly (P＜0.05). In the patients with U. urealyticum positive, the curvilinear velocity was (34.08±4.75) μm/s, straight line velocity was (23.40±3.02) μm/s, average path velocity was (27.08±3.57) μm/s, movement angle was (47.81± 5.83)°and beat-cross frequency was (5.03±0.59) % and the differences were significant (P＜0.05). In the patients with U. urealyticum positive, the normal rate of α-glucosidase was 50.85%, which was significantly higher than that in patients with U. urealyticum negative (P＜0.05). CONCLUSION In the male infertility, the infection of U. urealyticum in the reproductive tract is relatively high, and the semen parameters and sperm motility are affected, which leads to a significant reduction in semen quality, causing male infertility.