The invention provides a pre-heating method of sulfate slag pellet ore. The method comprises the steps of: sending sulfate slag green pellets into a chain grate for to be subject to forced air drying,draft air drying, primary pre-heating and secondary pre-heating in sequence; taking the fume discharged by a rotary kiln as the hot air source during the secondary pre-heating; taking the fume discharged by secondary cooling of a cooler as the hot air source during the primary pre-heating; taking the fume discharged after secondary pre-heating as the hot air source during the draft air drying; and taking the fume discharged by tertiary cooling of the cooler as the hot air source during the forced air drying. The invention firstly carrying out forced air drying on the sulfate slag pellets, when the moisture of the green pellets move upwards from the bottom of the material layer, thus preventing an overdamp layer from being formed on the bottom layer of the material layer, avoiding the appearance of flattened or cracked green pellets on the bottom of the material layer and ensuring the following procedures to be carried out smoothly.