The invention relates to a deepwater semi-submerged drilling platform, which comprises floating tanks, an upright post, a transverse supporting rod and a main deck, wherein a drilling block is arranged above a moon pool in the middle of the main deck; and a derrick is arranged on the drilling block. The deepwater semi-submerged drilling platform is characterized in that: a half derrick space for pre-connecting a drilling tool is reserved on one side of the derrick; a water isolating pipe, a drilling stem, a blowout preventer and a production tree are arranged on the main deck around the moon pool respectively; and an anchor moored positioning and dynamic positioning combined position system which consists of front and back four groups of anchor gears distributed on the left and right sides of the main deck is adopted, each group of anchor gears are provided with 3 anchor chains, a dynamic positioning system consists of 8 dynamic thrusters capable of rotating 360 degrees at the front and back four corners of the bottom of the two floating tanks. In the deepwater semi-submerged drilling platform, the maximum operation water depth is up to 3,000 meters, the maximum drilling depth is up to 12,000 meters, and the maximum variable load is up to 9,000 tons. The deepwater semi-submerged drilling platform can operate in the South China Sea, Southeast Asian sea area and West Africa sea area with severe sea conditions efficiently and safely.