In this paper, according to the characters of wavefield propagation in medium and the multivariate statistical analysis, a ML criterion, which fits the data with the model is reached by strict mathematical derivation, is used to test whether the energy of specific wave type is present. The decomposed seismogram is obtained by using probability filtering, the arrived time can be find out from it directly. The technique is satisfactory for P waves, but is sometimes a little poor for S waves, which is probably due to the correlation between radial and transverse components. Especially for split shear waves, the arrival time obtained by this method, should be that of fast shear waves. Practical examples shown that the method is very available for the processing of three component recordings.