The present invention relates to a bathroom directional drainage method which comprises a step of storing GPS data of each allowable discharge area and also storing preset outline features of the allowable discharge areas, a step of collecting and outputting a current GPS position of a compartment where a high-speed railway toilet is located, a step of collecting and outputting a high-definition image under the compartment where the high-speed railway toilet is located, a step of determining whether compartment where the high-speed railway toilet is located is above an allowable discharge areaor not based on the current GPS position of the compartment where the high-speed railway toilet is located, the GPS data of each allowable discharge area, the preset outline features of the allowabledischarge areas and the high-definition image under the compartment where the high-speed railway toilet is located, and emitting a discharge allowance signal if so, otherwise emitting a discharge prohibition signal, and a step of receiving the discharge allowance signal or the discharge prohibition signal and performing a directional discharge operation when the discharge allowance signal is received.