Abstract: Provided are a slot-hole showerhead structure for a leading edge of a turbine guide vane and a design method thereof. The structure includes a plurality of rows of slot holes formed in a leading edge of a vane, where a quantity of hole rows is determined based on a total mass flow rate of a coolant and a preset blowing ratio range; a hole row spacing is determined via iterative optimization; and an exit of each slot hole has a special rotation angle. The design method includes: determining the quantity of hole rows according to the total mass flow rate of the coolant and the preset blowing ratio range; with the peak value of the cooling effectiveness as a target, iteratively optimizing the hole row spacing row by row; and quantitatively computing an exit rotation angle of the slot hole based on an aerodynamic parameter.