Four earthquakes with magnitude around M6.0 are studied based on six seismic wave parameters, which occurred in southeastern China since 1970. These seismic parameters include rupture characteristics ( ); primary rupture directions; ambient shear stress ; temporal periodicity of waveform ; -values for P waves; and the width of Fourier spectrum . In this study, the six parameters for each earthquake are calculated, compared, and investigated in order to define single foreshocks. Errors caused by the digitization of analogue record and the application of simplified hypocenter and medium models, as well as errors generated in measuring earthquake magnitude and hypocentral radius are estimated and discussed. Primary characteristics of earthquakes occurred within the seismogenic zones and seismic belts are presented after processing 510 charts, 135 earthquakes, and 1030 records.