Four methods were used to determine SiC content of self-combined 95 silicon-carbide brick, such as hydrofluoric acid volatilization-gravimetric method, direct method, etc. Results of different methods were compared, and causes of the difference were identified. The test results indicate that impurities compositions have different effects on different test methods. When impurities are free carbon, free silica, iron oxide, silicon oxide, hydrofluoric acid volatilization-gravimetric method is appropriate. When hydrochloric acid-resist impurities are more, it is necessary to choose direct and indirect methods. When using direct method and indirect methods, it is useful to increase the amount of flux to make sure that the specimen is dissolved thoroughly. If necessary, increasing test times is useful.