A capillary magnetic-liquid sealing device includes: a housing having a shaft chamber; a rotating shaft arranged in the shaft chamber; a first pole shoe and a second pole shoe fitted over the rotating shaft and spaced apart in an axial direction of the rotating shaft; a permanent magnet fitted over the rotating shaft and located between the first pole shoe and the second pole shoe; a first magnetically nonconductive capillary block and a second magnetically nonconductive capillary block fitted over the rotating shaft and spaced apart in the axial direction of the rotating shaft. A first capillary cavity is formed among the first magnetically nonconductive capillary block, the first pole shoe and the rotating shaft; and a second capillary cavity is formed among the second magnetically nonconductive capillary block, the second pole shoe and the rotating shaft.