The invention relates to a method for alarming about hourly overcapacity of an airport and a device thereof; wherein, the method comprises the following steps: flight service conditions of a certain related airport on the same day are obtained from a flight service information database at the same day throughout the country; statistic is carried out on hourly number of flights of the airport at the same day according to flight service information of the airport at the same day; comparing the hourly number of flights of the airport at the same day with preset hourly standard capacity value of the airport at the same day; when the hourly number is larger than the hourly standard capacity value, an overcapacity alarming signal is sent. The device of the invention comprises an information acquisition unit, a flight number statistical unit and an overcapacity alarming unit. In the invention, real-time monitoring of the hourly capacity of the airport is realized and the purpose of alarming about hourly overcapacity is achieved, therefore, the method and the device of the invention are of great significance in rationally arranging taking off and landing time slot of flights, ensuring highly effective and stable operation of taking off and landing flights in the airport, reducing flight delay caused by airport congestion and improving efficiency ratio of flight operating charges.