A method is proposed to automatically analyze energy dispersive X- ray fluorescence (EDXRF) spectrum fast and accurately. Smoothing of spectrum, background subtraction and peak searching are used in the method. It not only can be applied to analyze single spectrum, but also can be used for analyzing a large number of spectra continuously. The method is evaluated by using the spectrum analyzed by micro- X- ray fluorescence in laboratory. Compared with Gaussian fitting, the result of the symmetric zero area method is basically the same but this method has the advantage of short computing time. It can obtain a good result in the case of the spectrum with big noise and well ability of picking out the weak peaks. On ordinary PC, the average time of analyzing a single file is less than 1 s while analyzing hundreds of files using this method. It can obviously reduce the work time and improve work efficiency.