Analysis and research on the fault-gas precursorg phenomena before the Jingtai M6.2 Earthquake are made based on a lot of data. Tha results show that the gases Rn and CO₂ at Guyuan site on the earthquake-generating fault and gases Hg and H₂ at the nearest Gulang site from seismic center have very distinctive medium-long term,short term and impending earthquake precursors. The extent of this earthquake an0maly is up to more than 500 km,associated with 13 kinds and/or times of gas anomalies,in which Hg and H₂have the most informations. Kesearches also suggest that the sudden variation of He and Ne is the expression of increasing activity of the fault,and is medium term precursor of the present strong earenguake,because He and Ne are product of nuclear fusion in depth of the earfh.