A SiO2-SiC coating on 3-D carbon fiber perform (raw perform) was successfully prepared through several steps. The appearance and composition of the coating/3-D carbon fiber preform (coated perform=CP) was studied through IR, XRD and SEM. The isothermal weight-loss and non-isothermal thermogravimetric (TGA) were used to study the oxidation behavior of CP. The results showed that a uniform coating on every fiber of preform was achieved and the coating adhered well with fiber. The oxidation process of CP in isothermal condition was reaction-controlled in the first step, gas diffusion and reaction-controlled in the second step. The characteristic of the oxidation process in non-isothermal condition was self-catalytic.