A superdeep Middle Proterozoic Wumishan carbonate buried hill oil and gas reservoir, which is deep buried within Baxian Sag, Jizhong Depression, was discovered in Well ND-1 in January, 2011. The drilled depth reached to 6027 m at the bottom of the Niudong-1 buried-hill reservoir where no oil/water interface was met and the temperature is at 201℃(about 394℉) at the well bottom. The acid-fracturing well test gave the high output rate of 642.9 m3 oil and 563×103 m3 natural gas per day. It is the oil and gas reservoir with the greatest well depth, the highest output and the highest well-bottom temperature that has discovered up to now in Bohaiwan Basin, even in the eastern part of China. The exploration history for more than 30 years that has undergone from failure, through putting-aside and reviving to success is reviewed. Three key technology and their important actions playing in exploration are described. The first technology is the "high-precision gravimetric and magnetic survey" that supplied important clue for the discovery of the superdeep buried hill, the second one is the "secondary 3-D seismic survey" that achieved the accurate orientation for the buried hill trap, and the third one is the "high-T-resisting, deepening and voluminous acid-fracturing" that supplied the effective technology ensure for well testing to obtain high oil and gas output in the superdeep and superhigh T reservoir.