The invention relates to a preparation method for uvioresistant and cationic dyeable polyester chip, which comprises an esterification reaction procedure, an ester exchange procedure and a polymerization procedure in sequence, wherein three monomers are added in the ester exchange procedure; hindered anime light stabilizer and hindered phenol antioxygen are added after the esterification and before prepolymerization; and ultraviolet absorbent is added after the prepolymerization and before the final polymerization of the polymerization procedure. Fabric prepared by the fiber spun by the polyester chip has good uvioresistant effect. Meanwhile, the fabric can be dyed into various beautiful colors through the cationic dye characteristic of the polyester chip. The unified requirements of top grade spring and summer clothes on function and color are satisfied. The cationic dyeable polyester chip has broad market prospect and is also an important supplementation for the domestic current cationic dyeable polyester fiber market.