The invention provides a resistance mechanism with a self-locking function, which is used in fitness equipment, and comprises a motor, a hoisting mechanism and a self-locking driving mechanism, the self-locking driving mechanism is used for locking and unlocking the rotation of the hoisting mechanism, the self-locking driving mechanism is arranged in a span range of a winding space, and the self-locking driving mechanism is used for driving the hoisting mechanism to rotate. The self-locking driving mechanism comprises a driving unit and a second locking matching unit, and the driving unit is used for driving the second locking matching unit to be connected with or separated from the first locking matching unit, so that the rotation of the hoisting mechanism is locked and unlocked. The self-locking driving mechanism is located in the span range of the winding space, so that the winding space can be used for arranging the self-locking driving mechanism, the overall size of the resistance mechanism with the self-locking function is smaller, and full utilization of the space of fitness equipment and
miniaturization of products are facilitated.