〔Abstract〕 Objective To investigate the effects effect of lncRNA CASC2 on inflammation, migration and invasion of rheumatoid arthritis(RA) synovial fibroblasts by regulating the expression of miR-218-5 p and its mechanism. Methods 45 cases of RA synovial tissue and 18 cases of normal synovial tissue were collected, and qRT-PCR was used to detect the expression of CASC2 and miR-218-5 p in the synovial tissue. ENCORI prediction and dual luciferase reporting experiments analyzed the targeting between CASC2 and miR-218-5 p. RA synovial fibroblast MH7 A were transfected with pcDNA3.1-CASC2 and miR-218-5 p mimic, the expression of CASC2 and miR-218-5 p was detected by qRT-PCR; CCK-8 was used to detect cell proliferation; ELISA was used to detect the levels of tumor necrosis factor-α(TNF-α), interleukin-1β(IL-1β) and interleukin-6(IL-6) in the supernatant of cells; Transwell was used to detect migration and invasion of cells; Western blot was used to detect expression of matrix metalloenzymes MMP-2 and MMP-9. Results Compared with normal synovial tissue, RA synovial tissue showed significantly down-regulated expressions of CASC2(P<0.05)and up-regulated expressions of miR-1236-3 p(P<0.05). The dual luciferase reporter showed that CASC2 was target genes of miR-218-5 p. Overexpression of CASC2 significantly suppressed cell proliferation, reduced the levels of TNF-α, IL-1β and IL-6 in the supernatant and migration and invasion, lowered the levels of miR-218-5 p and protein expression of MMP-2 and MMP-9 in RA synovial fibroblast MH7 A. However, transfecting miR-218-5 p mimic could reverse the situation. Conclusion RA synovial tissue showed significantly down-regulated expressions of CASC2, overexpression of CASC2 suppressed inflammation, migration and invasion of RA fibroblasts by regulating the expression of miR-218-5 p.