The invention discloses a method and a system for quickly and directly processing an original signal into a plurality of mode functions, the steps comprises: decomposing the original signal by Empirical Mode Decomposition (EMD) method to choose a first intrinsic mode functions (IMFs). Then, adding the plurality of level n conjugate masking functions, which are selected from a group of sinusoidal functions comprising the mean amplitude and the mean frequency of the first IMF, to the original signal individually to obtain level n mode functions, until the level n mode function is a monotonic function, wherein the plurality of mode functions are the IMFs between each frequency regions of the original signal. The invention not only includes the advantage of EMD analyzing, but also excludes the problem of mode mixing phenomenon which is caused by the intermittent disturbance.
