Abstract: The Haicheng earthquake (Feb. 4, 1975, M=7.3) has caused the extensive liquefaction of sand in the Lower Liaohe River region, which expressed itself as ejected water and sandflows, sundken lands and sandy holes on ground surface, ground drumlings, landslides and ground fissures.According to the degree of ejection and ground failure the liquefied region may be classified into three areas different in hazard, i. e. intensive(I), moderate(Ⅱ) and weak (IE). The liquefied region in the Lower Liaohe River has been a regression area in Holocene period, covered by a layer of clayey soil with a thickness of 2-5m. This layer is thinner in the intensive hazard area with a higher aquifer head, but thicker in the weak hazard area with a lower head.The monograin structure of ejected sands shows the loosening nature of liquefied sandy layer. In the intensive hazard area the sand grains ejected are found to be coarser. According to the present analysis of sand grains it is concluded that the roundness of grains is of less importance in determining whether a sandy soil can be readily liquefied or not.