A support frame includes first and second mounting members, and an adjusting member. The second mounting member defines a groove. One groove wall of the groove defines a plurality of positioning holes. The adjusting member includes a base body, a sliding member, and an elastic member. The base body is disposed on the first mounting member, and at least a part of the base body is accommodated in the groove. The sliding member is slidably disposed on the base body and includes a clamping body. The elastic member is disposed on the sliding member, and the elastic member can drive the sliding member to engage the clamping body with one of the plurality of positioning holes. When the support frame is in a cabinet, an interior installation size of the cabinet is adjustable for any particular relative position between the first and second mounting members.