A method of detecting atrial fibrillation includes detecting a pulse signal to obtain a time pulse waveform and converting it to an energy spectrum waveform via Fast Fourier Transform. The energy spectrum waveform includes a first frequency region, a second frequency region, and a third frequency region. The number of spikes in each frequency region was calculated and the heart indexes of the first, second, and third frequency regions were obtained, which were the first heart index, the second heart index, and the third heart index. And by the sum of the three heart index values and the first heart index to determine the possibility of atrial fibrillation. An apparatus for detecting atrial fibrillation is also provided, whereby the user can determine the possibility and predicting atrial fibrillation by simple measurement of blood pressure at home.