The invention provides a middle-depth-water semi-submersible type drilling platform which comprises two separated lower floating bodies, at least four stand columns vertically arranged on the two lower floating bodies, and a main ship body supported by the stand columns and of a square box structure. Each lower floating body comprises two fore and aft sections and one middle section, wherein the two fore and aft sections are connected to the two longitudinal ends of the middle section respectively, each fore and aft section is of a structure with the width gradually decreasing from the middle to the two ends in the longitudinal direction, the maximum-width position of each fore and aft section smoothly transits to the outer end through a hook face, a cambered surface is formed at the outer end of each fore and aft section, the maximum-width position of each fore and aft section is connected with the hook face of the middle section in a smooth transition mode, and the maximum width of the middle section is smaller than the maximum width of each fore and aft section. The stand columns are vertically arranged on the fore and aft sections of the lower floating bodies. The towing and self-propelling resistance of the drilling platform is reduced, fuel oil consumption is reduced, and operating cost is reduced. Furthermore, the heaving motion amplitude response operator of the platform can be reduced, and platform heaving performance is improved.