Abstract: The prefabricating rack frame are comprised of a column and a cross member. The column have plural slots along a longitudinal direction at an even interval, and the cross member have a pair of hooks to be inserted into respective slot, and a location restrictor is formed between the upper and the lower hook and bent rectangular to the hook, and tightly contracted on the outer surface of the column. The cross member further has a pit and a reinforcement rib; the pit is formed at the outer corner where each longitudinal end of the cross member meets the foot of the location restrictor; and a reinforcement rib is provided at the inner corner of the location restrictor and its configuration counterposes to that of the pit.