The invention discloses a mining supporting device convenient to mount. The mining supporting device comprises a supporting cross beam for C-shaped groove steel. Supporting heads are connected to thetwo ends of the supporting cross beam in an inserted mode and hinged to the supporting cross beam through supporting shafts. Upper supporting pipes are welded and fixed to the supporting heads. Adjusting screw rods are in threaded connection with the interiors of the upper supporting pipes. The lower ends of the adjusting screw rods are in threaded connection with the interiors of lower supportingpipes. Circular bottom plates are welded and fixed to the bottom ends of the lower supporting pipes. A plurality of bolt passing holes are formed in the bottom plates. Reinforcing plates are welded and fixed to the inner side bottom surface of the middle of the supporting cross beam. Studs are formed on the reinforcing plates. Oblique supports are arranged between the lower supporting pipes and the supporting cross beam. The lower ends of the oblique supports are hinged to lower hinged seats through hinged shafts. The lower hinged seats are fixed to the outer walls of the upper ends of the lower supporting pipes. The upper ends of the oblique supports are hinged to upper hinged seats through hinged shafts. Kidney-type-hole-shaped inserting grooves are formed in the upper hinged seats. Thestuds on the reinforcing plates penetrate through the inserting grooves of the upper hinged seats to be in threaded connection with fastening nuts.