Cosmetic brush

A cosmetic brush, comprising:

• a main body, the main body comprising a front part, a rear part, and a liquid storage cavity disposed between the front part and the rear part;
• a front cover;
• a rear cover;
• a brush assembly;
• and
• a piston;
• wherein:
• the front cover is disposed on the front part and the rear cover is disposed on the rear part;
• the brush assembly is disposed in the front part;
• the piston is disposed in the rear part;
• the brush assembly and the piston are disposed at two ends of the liquid storage cavity, respectively;
• the rear cover is rotatably disposed relative to the main body;
• the rear cover is provided with a rear cover sleeve, and the rear cover sleeve is fixed on the rear cover;
• the rear cover comprises a threaded rod and a plurality of threaded sleeves;
• the plurality of threaded sleeves is telescopic and is hinged to one another via screw threads, and comprises an innermost threaded sleeve and an outermost threaded sleeve;
• the threaded rod comprises a first end and a second end;
• the first end of the threaded rod abuts against the piston, and the second end of the threaded rod is in threaded connection to the innermost threaded sleeve;
• the outermost threaded sleeve is in threaded connection to the rear cover;
• and
• the outermost threaded rod comprises a plurality of axially-distributed grooves, and the rear cover comprises a plurality of axially-distributed ribs corresponding to the grooves;
• the outermost threaded rod is engaged with the rear cover via the grooves and ribs.