Objective: To explore the role of ubiquitin proteasome system in the pathogenesis of infection related preterm birth. Materials and Methods: Thirteen women with spontaneous preterm delivery and 13 controls were included in present case-controlled study. The mRNA and protein levels of Ub-conjugating enzyme E2Q1 (UBE2Q1) and Carboxyl-terminus of Hsc70 interacting protein (CHIP) in the placenta were measured by immunohistochemistry, real-time RT-PCR, and Western blotting methods. Statistical significance (p < 0.05) was determined using student's t-test. Results: The mRNA levels of UBE2Q1 (0.48±0.05 vs. 0.67±0.07, p = 0.047) and CHIP (1.59±0.23 vs. 5.62±1.00, p = 0.002) in the placentas of preterm delivery were significant lower than those of term delivery. The protein levels of UBE2Q1 (0.64±0.09 vs. 1.49±0.22, p < 0.001) and CHIP (0.76±0.08 vs. 1.33±0.23, p = 0.001) in the placentas of preterm delivery were also significant lower than those of term delivery. Conclusions: Decreased mRNA and protein expression of UBE2Q1 and CHIP were both found in the syncytiotrophoblast and cytotrophoblast of placenta in preterm birth patients, which was speculated to play a role in the pathogenesis of infection related preterm birth.