A casing structure having a removable base frame includes a casing and a base frame. The casing includes a bottom plate, wall plates, and a bracket disposed on the bottom plate. A top stopper is erected on the bracket. The base frame has a frame plate for disposing the base frame astride the wall plates. The base frame is also disposed with a mounting plate corresponding to the top stopper. The mounting plate has a rotatable push-actuated member. When the push-actuated member rotates and is pressed against the top stopper, the base frame is pushed up and removed from the casing.