A heat-dissipating unit having a hydrophilic compound film and a method for depositing a hydrophilic compound film are disclosed. The heat-dissipating unit includes a metallic body having a chamber and a working fluid. The chamber has a liquid-guiding structure constituted of an evaporating portion, a condensing portion and a connecting portion. At least one hydrophilic compound film is coated on surfaces of the chamber and the liquid-guiding structure. By this arrangement, the flowing of the working fluid in the heat-dissipating unit is enhanced to improve the heat-conducting efficiency of the heat-dissipating unit.