The invention relates to a preparation method for a polyester fiber with a composite ultraviolet, static electricity and pilling resisting function. The preparation method comprises an esterification reaction procedure, a polymerization reaction procedure and a spinning procedure. The esterification reaction procedure comprises a primary esterification reaction stage and a secondary esterification reaction stage, flexible polyethylene glycol is introduced as a third monomer in the secondary esterification reaction stage, and after esterification is finished, a hindered amine light stabilizer,a hindered phenol anti-oxidant and hydroxyl silicone oil are added, wherein the hindered amine light stabilizer and the hindered phenol anti-oxidant are prepared by taking an acetic acid and ethyleneglycol as solvents. In the polymerization reaction procedure, after prepolymerization and before final polymerization, an ultraviolet absorbent and an antistatic agent are added. Before the spinning procedure, polyester is sliced for pre-crystallization and drying. The polyester fiber obtained by the method has the outstanding ultraviolet, static electricity and pilling resisting functions, and after being woven into knitted machine-made fabrics, is tested to have related technical indexes comprising the ultraviolet light transmittance of less than or equal to 5.0%, the pilling resistance of more than or equal to level 4 and the fiber volume specific resistance of less than or equal to 10*10<10> ohm.cm.