The invention provides a sleep apnea detection system and method. The system includes a detecting module, a processing module, a converting module and a determining module. The detecting module detects a plurality of peak time points of R-waves in an ECG (electrocardiograph) signal. The processing module calculates areas of the R-waves at a predetermined time range based on the peak time points, so as to produce a plurality of first R-wave area signals based on the areas and generate an EDR (ECG Derived Respiration) signal based on the peak time points and the first R-wave area signals. The converting module converts the EDR signal to a frequency signal. The determining module determines whether a maximum peak frequency of the frequency signal is at a first frequency segment or a second frequency segment to determine the frequency signal being an apnea signal or a normal breathing signal.
