Osteoarthritis is an age-related disorder of bone-joint that causes pain and disability in middle and older people. This study aimed to investigate the potential effects of long non-coding RNA (lncRNA) THRIL on lipopolysaccharide (LPS)-induced osteoarthritis cell injury model (ATDC5 cell inflammatory injury), as well as the possible internal molecular mechanisms. Cell viability and apoptosis were assessed using CCK-8 assay and Guava Nexin assay, respectively. Cell transfection was conducted to change the expression of THRIL and microRNA-125b (miR-125b) in ATDC5 cells. qRT-PCR was performed to detect the expression of THRIL, miR-125b and pro-inflammatory cytokines IL-6, TNF-α and monocyte chemotactic protein 1 (MCP-1) in ATDC5 cells. ELISA was used to measure the concentrations of IL-6, TNF-α and MCP-1 in culture supernatant of ATDC5 cells. Finally, the protein expression of key factors involved in cell apoptosis, inflammatory response, JAK1/STAT3 and NF-κB pathways were evaluated using western blotting. LPS significantly induced ATDC5 cell inflammatory injury and up-regulated the expression of THRIL. Overexpression of THRIL aggravated the LPS-induced ATDC5 cell inflammatory injury. Suppression of THRIL had opposite effects. Moreover, THRIL negatively regulated the expression of miR-125b in ATDC5 cells. miR-125b participated in the effects of THRIL overexpression on LPS-induced ATDC5 cell inflammatory injury. Furthermore, overexpression of THRIL enhanced the LPS-induced JAK1/STAT3 and NF-κB pathways activation by down-regulating miR-125b. THRIL exerted pro-inflammatory roles in LPS-induced osteoarthritis cell injury model. Overexpression of THRIL promoted LPS-induced ATDC5 cell inflammatory injury by down-regulating miR-125b and then activating JAK1/STAT3 and NF-κB pathways.