This　paper　presents　a　BFSK　demodulation　method　using　Discrete　Short-Time　Fourier　Transform　(DSTFT).　The　method　discusses　the　BFSK　signal　in　time-frequency　domain,　which　is　different　from　conventional　demodulation　methods.　The　principle　of　demodulation　and　a　new　code　synchronization　algorithm　are　given　in　the　paper,　different　window　functions　are　tried　during　the　simulation,　which　bring　different　demodulated　performance.　And　the　test　results　indicates　the　demodulation　is　all　right.