Portable secondary debugging dolly for the inconvenient problem of instrument transport in the problem transformer maintenance operation of solution. Including automobile body and handle, be equipped with the universal wheel at bottom of the car body, the handle hinges with the automobile body to be connected, is equipped with to be used for fixing the upper and lower locking mechanism with handle and automobile body on the automobile body, be equipped with diaphragm and a pair of riser in the inner chamber of automobile body, diaphragm and riser fall into four cavitys with the inner chamber of automobile body, and articulated outside left two cavitys have little, state and are equipped with positioning mechanism between little door and the riser, be equipped with a pair of flexible door respectively outside every cavity on right side, flexible door include with automobile body articulated planking, place in the planking inboard and with planking sliding connection's inner panel, be equipped with the lock between two mated inner panels. This dolly can be used for placing equipment such as instrument and meter, solenoid, cable drum and observing and controlling check gauge and in the time need not using this dolly, lift the handle off from last locking ware, and it can in hiding the groove to fold.