Aim Ubiquitin-proteasome pathway is an important pathway of protein degradation in cells, it is involved in many physiological processes including cell cycle regulation, DNA repair and cell apoptosis. To study the effect of ubiquitin-pro teasome pathway on apoptosis in THP-1 cells and the possible mechanism of apoptosis, THP-1 cells were treated and the related indexes were detected. Methods THP-1 cells were treated with MG132 (5 μmol/L) for 24 h. Ubiquitin, ubiquitin-activat ing enzyme (E1), ubiquitin-conjugating enzyme (E₂), ubiquitin-protein ligase (E3) and 26S proteasome genes expression were detected by reverse transcription-polymerase chain reaction (RT-PCR). Apolipoprotein B (ApoB) concentration in THP-1 cells and cell apoptosis rate were detected by flow cytometric analysis (FCA). Results RT-PCR showed that E1, E₂, E3 genes expression were decreased in treatment group and the concentration of ApoB and apoptosis rate were increased obviusly. Conclusions Protesome inhibitr MG132 could inhibit the expression of E1, E₂ and E3, UPP activity was inhibited. Degradation of ApoB decreased and so cell apoptosis rate increased. The apoptosis of macrophages in the early stage of atherosclerosis could delay the atherogenesis. This experiment is to detect the novel mechanism of macrophages from the regulation of ubiquitin-proteasome pathway, it could be a new target to prevent the atherogenesis.