A brushless DC motor control system for a ceiling fan is electrically connected to a brushless DC motor, and includes a first switch, a detection module, a timer, a processing module, and a driving module. The first switch sends a first switch signal to the detection module for detection. The detection module outputs an operating electric potential detection signal to the timer. The timer outputs an operating electric potential timing signal to the processing module, so that the processing module outputs a first control signal and a second control signal to the driving module for controlling the brushless DC motor to change the rotational speed and the rotational direction respectively, increasing the convenience of use.