The invention discloses a tension control method which comprises the steps: 1, unreeling a tape coil by an unreeling roll, and winding the unreeled tape coil onto a reeling roll through a tension roll; 2, acquiring the original roll diameters of the unreeling roll and the reeling roll; 3, acquiring time-varying real-time roll diameter(s) of the unreeling roll and/or the reeling roll in a tape coil winding process; 4, integrating input information in the steps 2 and 3, carrying out an interpolation operation on the input information, respectively working out rotation positions of motors of the unreeling roll and the reeling roll once the tape coil is wound by a distance L, and respectively outputting the rotation positions to the motor of the unreeling roll and the motor of the reeling roll through an information output unit; and 5, running the motor of the unreeling roll and the motor of the reeling roll according to the position information output in the step 4, wherein the interpolation operation in the step 4 is that an interpolator carries out calculation on pulses required by the rotation of the motors or a bus controller carries out the calculation on the positions of the rotation periods of the motors. The tension control method disclosed by the invention is simple in control manner, easy to realize, high in control precision and good in system operation stability.