To　solve　the　problems　of　resisting　to　joint　attacks　and　the　low　extraction　accuracy　rate　that　exist　in　present　digital　watermarking　algorithms,　a　block　fast　fourier　transtorm　(FFT)　based　on　digital　watermarking　algorithm　was　proposed.　The　algorithm　normalized　the　image　size　and　modified　the　values　of　blocked　FFT　coefficients　according　to　the　watermark.　Watermark　was　embedded　in　accordance　with　the　dual　circulation.　When　extracting,　the　values　of　FFT　coefficients　indicated　the　watermark.　Experimental　results　show　that　this　algorithm　can　increase　resistance　to　noise　filtering　and　other　conventional　signal　processing　attacks;　JPEG　compression;　rotation,　translation　and　scaling　attack;　cropping　and　splicing　attacks;　and　their　combined　attack.　The　bit　error　rate　is　almost　0.