Abstract: A new type of inorganic heavy liquid,LST(solution of lithium heteropolytungstates in water),used in microfossils or mineral grains separation,is introduced in this paper,for it has the advantages of non-toxic,lower viscosity,high density,high resistance to decomposition and high recycle rate.Based on the rich experiences in conodont separation,this paper describes in detail the procedure of the preparation,using and recycling of the LST heavy liquid.For the most efficient separation,a 2.80-2.81g/mL density of heavy liquid is recommended for limestone samples,while a 2.82-2.83g/mL density of heavy liquid is recommended for dolomite samples.Compared with the traditional heavy liquids,e.g.bromoform,tetrabromoethane,diiodomethane,thoulet solution and sodium polytungstate,LST heavy liquid has distinct superiority.We strongly suggest that the traditional organic and inorganic heavy liquids should be replaced by LST heavy liquid in separating microfossils and minerals.