Abstract: Xylotrechus namanganensis is a kind of devastating borer to many broad leaved tree species in Xinjiang.Its spatial distribution model has been studied since 1996.The result showed that the number of adult eclosion cavity on the trunk of elm trees with the height of 0～0.5 m,and 0～2.5 m above the ground belonged to assembly distribution model by testing the indexes such as C,I,M*,M*/,X,K and CA .Checking tests by method of Iwao and Taylor also consistently draw out the same conclusion.The sampling numbers of elm trees can be determined by the formulae N=143.26/X+15.78 and N=345.63/X+13.04 respectively if the number of eclosion cavity on the trunk with the height of 0～0.5 m,or 0～2.5 m above ground is to be investigated by Iwao method.On the basis of recognizing that eclosion cavity spatial distribution of Xylotrechus namanganensis on the trunk of elm trees belonged to assembly distribution model,and the economic injury level (EIL) was 2 eclosion cavities on the trunk,the upper and lower limits of sampling number can be calculated by formula T0(n)=2N±8.1797√N.