Objective：To explore the role and mechanism of circular RNA FAT1(hsa_circ_0001461)-miR-181d-5p/miR-199a-5p axis in the biological functions of oral squamous cell carcinoma(OSCC)cells. Methods：The clinical tissues of 30 OSCC patients were collected，and the expressions of circFAT1，miR -181d -5p and miR -199a -5p in OSCC tissues and cells were detected by real -time quantitative PCR. starBase and dual luciferase reporter genes were used to verify the targeting relationship between miR-181d-5p/miR- 199a-5p and circFAT1. Functional experiments include CCK-8，Transwell，and flow cytometry to detect the effects of circFAT1-miR- 181d-5p/miR-199a-5p axis on OSCC cell viability，migration，invasion，apoptosis and cycle. Western blot combined with LY294002 treatment was used to detect the expression of PI3K/Akt/mTOR signaling pathway related proteins. Results：The circFAT1 expression increased，and miR-181d-5p and miR-199a-5p expressions decreased in OSCC(P ＜ 0.001). CircFAT1 could target miR-181d-5p and miR-199a-5p(P ＜ 0.01). Silencing circFAT1，miR-181d-5p mimic and miR-199a-5p mimic inhibited OSCC cell viability，migration， invasion and cycle progression，induced apoptosis，and inhibited the activation of PI3K/Akt/mTOR pathway；overexpressed circFAT1， miR-181d-5p inhibitor and miR-199a-5p inhibitor played the opposing roles(P ＜ 0.05). MiR-181d-5p and miR-199a-5p partially reversed the effect of circFAT1 on the biological functions of OSCC cells(P ＜ 0.05). LY294002 pretreatment reversed the effect of overexpression of circFAT1 on PI3K/Akt/mTOR pathway and cell viability(P ＜ 0.05). Conclusion：circFAT1 promotes the malignant progression of OSCC cells by miR-181d-5p/miR-199a-5p.