The present invention provides a testing machine for accurately controlling looseness of a transverse load, and belongs to the technical field of mechanical testing devices. The testing machine for accurately controlling looseness of the transverse load uses a motor to control the generated transverse displacement, controls the generated transverse load by controlling the motor, and controls the motor through signal feedback from the sensor to keep the generated transverse load basically stable within a small range of a fixed value. Unlike the existing testing machine for looseness of the transverse load that can only provide one fixed transverse displacement load, the present invention can provide a desired stable transverse displacement load and can provide a desired stable transverse force load to adapt to simulation experiments for different bolt loading conditions.