The invention discloses a D-column upper end joint structure which comprises a top cover, a rear beam outer board, a rear beam inner board, an Upper D-column reinforcing board, a rear surrounding outer board, an Upper D-column outer board and a rear surrounding inner board. The rear surrounding outer board is welded and fixed to the Upper D-column outer board. The cut edge of the Upper D-column reinforcing board and the cut edge of the rear surrounding inner board are arranged in a staggered mode. The Upper D-column reinforcing board is of an L shape, an arc transitional section is arranged in the middle of the Upper D-column reinforcing board, and the upper portion of the Upper D-column reinforcing board extends to one side so that an extending portion can be formed. An inward-recessed arc elbow is arranged at the top of the rear surrounding inner board. The root portion of the extending portion is welded to the arc elbow of the rear surrounding inner board. The Upper D-column reinforcing board and the rear beam outer board are detachably and fixedly connected. The Upper D-column outer board is welded and fixed to the rear beam outer board. The Upper D-column outer board, the rear beam outer board and the top cover are welded and fixed. According to the D-column upper end joint structure, the structure is simple, stress concentration is effectively reduced, the phenomenon that stress concentration is generated due to the arrangement of a notch is avoided, the part forming efficiency and the material use rate are improved, and the modality of a body in white is improved.