The invention provides a sealing structure for an engraving, milling and grinding electric spindle, and relates to a sealing structure for magnetic liquid. An internal thread of a non-flux sleeve (9) forming the sealing component is connected with a thread of a rotor (1); a flux locking ring (3) is connected with a bearing support (10) by screw thread; a right pole terminal (6) is arranged at thebottom end of an annular hole in the flux locking ring (3); the magnetic liquid is injected in a clearance between the right pole terminal (6) and the flux locking ring (3); a permanent magnet (5), and a left pole terminal (4) are arranged at the left end of the right pole terminal (6) in sequence; the magnetic liquid is injected into a clearance between the left pole terminal (4) and the flux locking ring (3); the non-flux sleeve (9), the flux locking ring (3), the right pole terminal (6) and the left pole terminal (4) form the sealing component; an annular groove on a gland bush (2) is matched with an annular gear of the left pole terminal (4) to form labyrinth seal. The invention solves the problems of short service life, complicated structure and large energy consumption of the engraving, milling and grinding electric spindle.