In longeriod magnetotelluric sounding measurement in the noisy area, the effective suppression of a variety of electromagnetic noises and the improvement of the quality of data constitute the core problem in long period magnetotelluric sounding data acquisition and data processing. As the longeriod magnetotelluric sounding data are characterized by nonlinear, nontationary and noninimum phase, in this paper the authors propose the EMD method to suppress the noise in longeriod magnetotelluric signals, and deals with the implementation details of the EMD algorithm. The authors applied the EMD algorithm to the longeriod magnetotelluric signal noise suppression, and the results show that the EMD method can effectively suppress the longeriod magnetotelluric noise.