Objective To investigate the effect of low-intensity pulsed ultrasound (LIPUS) on the extracellular matrix synthesis of human osteoarthritis (OA) chondrocytes and explore the underlying mechanism. Methods Human osteoarthritis chondrocytes were collected from abandoned articular cartilage. Then the cells were cultured and identified by toluidine blue staining and immunocytochemical staining of type 2 collagen. The passage 2 cells were randomly divided into 3 groups: control OA group, 30 mW/cm2 LIPUS-treated OA group, 30 mW/cm2 LIPUS combined with 5 μmol/L LY294002-treated OA group. LIPUS treatment was performed for 20 minutes per day, totally 7 days. The mRNA levels of Col2, aggrecan and matrix metalloprotease 13 (MMP-13) were determined by quantitative real-time PCR. The protein levels of Col2, aggrecan, Akt, p-Akt and MMP-13 were evaluated by Western blotting. Results Compared with the control OA group, the expressions of Col2 and aggrecan at both mRNA and protein levels significantly increased, and MMP-13 significantly reduced in the LIPUS-treated OA group. The p-Akt protein level was significantly elevated after LIPUS stimulation, but there was no significant difference in the Akt protein levels between the two groups. Moreover, LY294002, an inhibitor of PI3K/Akt, significantly suppressed the biological effect activated by LIPUS. Conclusion LIPUS enhances the synthesis and inhibits the degradation of the extracellular matrix in human osteoarthritis chondrocytes.