Abstract: Objective To investigate the regulatory effect of circular RNA centrosome and spindle pole-associated protein 1 (circCSPP1) regulating miR-495-3p/X-linked inhibitor of apoptosis protein (XIAP) axis on the proliferation, migration and invasion of cisplatin-resistant osteosarcoma cells. Methods Cell counting kit-8 (CCK-8) method was used to detect the half-maximal inhibitory concentration (IC₅₀) value of cisplatin on osteosarcoma cells (U2OS) and cisplatin-resistant osteosarcoma cells (U2OS/DDP). Dualluciferase reporter assay, RNA immunoprecipitation assay and RNA pull-down assay were utilized to analyze the targeting relationship among circCSPP1, miR-495-3p, and XIAP. The U2OS/DDP cells were divided into control group (untransfected), si-circCSPP1 group (transfected with circCSPP1 siRNA), si-NC group (transfected with siRNA negative control), miR-NC group (transfected with mimic negative control), miR-495-3p mimic group (transfected with miR-495-3p mimic), si-circCSPP1 + miR-495-3p inhibitor group (transfected with circCSPP1 siRNA and miR-495-3p inhibitor), pcDNA-NC group (transfected with overexpression negative control), and pcDNA-circCSPP1 group (transfected with circCSPP1 overexpression plasmid). Subsequently, real-time quantitative polymerase chain reaction detected the expression of circCSPP1, miR-495-3p, and XIAP mRNA; while Western blot was used to detect XIAP protein expression; CCK-8 method was used to detect the survival rate of U2OS/DDP cells; colony formation assays was used to detect the cloning ability of U2OS/DDP cells. Transwell experiment was used to detect migration and invasion of U2OS/DDP cells. Results The IC₅₀ values for the 1st, 3rd and 5th generations of U2OS/DDP cells were 23.44, 20.38 and 17.38 μg·mL^-1 respectively, which were significantly higher than those of U2OS cells (3.17, 3.06 and 2.79 μg·mL^-1), and the former were 7.39, 6.66 and 6.23 times those of the latter. Mechanistically, circCSPP1 directly interacted with miR-495-3p, and miR-495-3p directly interacted with XIAP. Compared with the control group and the si-NC group, miR-495-3p expression of U2OS/DDP cells in the si-circCSPP1 group was significantly increased (P < 0.05), and XIAP mRNA and protein expression, cell survival rate, colony formation number, migration number and invasion number were significantly reduced (P < 0.05). Compared with the control group and the miR-NC group, the XIAP mRNA and protein expression, cell survival rate, colony formation number, invasion number and migration number of U2OS/DDP cells in the miR- 495-3p mimic group were significantly reduced (P < 0.05). compared with the si-circCSPP1 group, the XIAP mRNA and protein expression, cell survival rate, colony formation number, invasion number and migration number of U2OS/DDP cells in the si-circCSPP1 + miR-495-3p inhibitor group were significantly increased (P < 0.05). Furthermore, compared with the control group and the pcDNA-NC group, the survival rate, colony formation number, invasion number and migration number of U2OS/DDP cells in the pcDNA-circCSPP1 group were all increased (P < 0.05). Conclusion Interfering with circCSPP1 could inhibit the proliferation, migration and invasion of cisplatin-resistant osteosarcoma cells by regulating the miR-495-3p/XIAP axis.