The invention discloses a portable automobile tailboard installing hydraulic device. The inclined top end of a U-shaped push rod is fixedly connected to the top end of a vertical strut of an L-shapedautomobile frame in a supported mode. The inclined bottom end of the U-shaped push rod is fixedly connected to a transverse frame body of the L-shaped automobile frame. A supporting plate is connectedto the outer wall of the inclined top end of the U-shaped push rod through welding. A top panel of the supporting plate is provided with an adjusting bolt I in the horizontal direction and a V-shapedsupporting block in the vertical direction. A vertically arranged adjusting bolt II is fixedly connected to the top end of the V-shaped supporting block. The adjusting bolt II is installed on the toppanel of the supporting plate in a perpendicular threaded connection mode. The bottom end of a shear type frame is rotationally connected to the transverse frame body of the L-shaped automobile frame. The top end of the shear type frame is rotationally connected with a lifting table. An adjusting bolt III in the horizontal direction is fixedly installed on the lifting table. Through the technicalscheme, the portable automobile tailboard installing hydraulic device is compact in structure, convenient to transport and use and high in accuracy, installing speed and efficiency of an automobile tailboard are promoted, and labor intensity is lowered.