Abstract: This paper deals with the stress field in the North China platform and has come to a conclusion that this area shows a difference of the horizontal stress in depth,higher in the eastern part and lower in the western part.Principal horizontal stress from various observation points increases with the depth in this area as well as in the Ordos uplifting region.In addition,the extensional stress appearsat a depth of 500 m.For the Beijing-Tianjing-Tangshan-Bohai area,the maximal principal compressive stress in depth is of ENE or nearly EW direction.At a depth of 30m from the surface the stress orientation relatively scatters and increases with depth below 30m,whereas shows a tendency of rotating.Decreasing of the minimal horizontal principal stress,or more,may he responsible for a trigger of the earthquake associated with a change in stresses.