The invention relates to the field of stratum drilling, and in particular to a control method and a control device for drilling operations. The control method comprises: detecting whether an overflow occurs in a well; controlling the wellhead back pressure based on a preset bottom hole pressure when no overflow occurs in the well, in order to keep the bottom hole pressure stable; and performing a shut-in operation and controlling the wellhead back pressure based on the increase in fluid discharge returned from an annulus of the well when an overflow occurs in the well, so as to keep the bottom hole pressure stable and prevent the gas in the stratum from continuing to invade into the drilling fluid during the process that the overflow drilling fluid is discharged from the bottom of the well. The control method and control device make it possible to prevent drastic fluctuation of the wellhead back pressure caused by the expansion of the invaded gases during the discharge thereof during the drilling operation, thereby realizing the stable control of the wellhead back pressure.