The invention belongs to a thermal control and cold control process of a steel rolling field and provides a thermal control and cold control process of ultralow-carbon fiber steel. A stepping type heating furnace is used for heating a steel blank, the temperature is required to reach 1150 DEG C at a soaking section and the heat is kept at the soaking section for a certain time; an opening rolling temperature is controlled at 1070+/-20 DEG C; after pre-finish-rolling rolling is finished, a rolling temperature is controlled, namely the temperature is firstly reduced to 910 DEG C through a water cooling manner and the steel blank enters a finish rolling machine to be rolled; after the steel blank is discharged out of the finish rolling machine, the temperature of a wire stock is controlled at 850+/-10 DEG C; final rolling is carried out and the temperature of the wire stock is reduced to 880+/-10 DEG C through one time of a temperature control process; and finally, spinning and molding are carried out to guarantee that the final temperature of discharging a cover is less than or equal to 400 DEG C and coil collection is finally carried out. The thermal control and cold control process can improve the drawing performance of a product; the product has a very high ductility and drawing performance; and meanwhile, the product has the higher extension strength.