The invention relates to a fastener pre-tightening force control device. The fastener pre-tightening force control device comprises a gear reducer, wherein the gear reducer comprises an output end, the output end comprises a connecting head and a magnetic column, the magnetic column comprises an N pole and an S pole, the N pole is arranged at one end of the magnetic column, the S pole is arrangedat the other end of the magnetic column, and a sensor for detecting the rotation angle of the magnetic column is further arranged on a box body. The fastener pre-tightening force control device has the advantages that the rotation angle of the output end is identified through the magnetic column arranged on the output end, due to the fact that the rotation angle of a fastener during tightening isin a proportional relation with the sum of the bolt elongation and the loosening amount of a tightened part, and the fact that the deformation elongation of the fastener in the elastic area is in direct proportion to the rotation angle of the fastener, the pre-tightening force of the fastener can be accurately controlled by controlling the rotation angle of the fastener, the pre-tightening force dispersion degree of the fastener can be reduced, the pre-tightening force of the fastener reaches 70%-80% of the yield limit, the utilization rate of a material is improved, the fixing quality of thefastener is also improved, and the effects of being safe and reliable are achieved.