This invention provides an image forming apparatus which performs fixing control complying with sheet characteristics in consideration of the productivity of a printing process and the precision of fixing control, and a control method thereof. To accomplish this, upon receiving a print job, the image forming apparatus extracts a sheet type used in the print job, and determines whether one set value in fixing control can be used for the extracted sheet type. If one set value can be used for the extracted sheet type, the image forming apparatus decides a common set value. If one set value cannot be used for the extracted sheet type, the image forming apparatus decides a set value for each type. In accordance with the decided set value, the image forming apparatus executes a printing process.