A position-limiting mechanism includes a first position-limiting element, a second position-limiting element, and a knob. The first and second position-limiting elements and the knob are slidably configured on a main body. A first component and a second component are secured to the main body by the first and second position-limiting elements, respectively. The knob is movably connected to the first and second position-limiting elements. When the knob slides relatively to the main body along a first direction, the knob drives the first position-limiting element to release the first component. When the knob slides relatively to the main body along a second direction, the knob drives the second position-limiting element to release the second component.