Based on the analysis of a portion of the far-field(△=300-450km) precursory data before the Manlai M 6.1 earthquake occurring in Mongolia on Aug.31.1992,this paper puts forward that an anomaly group with regional concentration and time-domain quasi-synchro-nism will probably be a universalism character of medium-term and short-term precursors during earthquake-pregnant process and. based on this concept.makes a reseach On the three seismic factors of time,space and strength.