Abstract: The pine bast scal(Matsueoecus matumurae Kuwana)is one of the most destructive pest of pines.In order to find out the resistance of different pines to this pest,incoulating tests have been carried out in Fuyang,Chekiang, China since 1979.The pine species tested are Pinus serotina Michaux,Pinus taeda Linnaeus,Pinus elliottii Engelmann,Pinus rigida Miller,Pinus eohinata Miller,Pinus glabra Walter,Pinus Patula Schlechtendal and Chamisso, Pinus palustris Miller,Pinus thunberghii Parlatore,Pinus luehuensis Mayr with the Massonian pine,Pinus massoniana Lamb;as check.Through two generations of inoculating tests and examinationes for many times,it has been found that the pine bast scale cannot develop or even alive on the former eight pine species,but it can develop on the latter two pine species.In other words,among the ten pine species tested only the latter two species are injured and attacked by the pine bast scale. Through the anatomy of branches of the above mentioned pine species and the analysis of the content of protein,sugar,fat,amino acid,water,gum and gum acid,it is shown that there are no longleaf pine acid,levopimarie acid and new abietic acid in the gum acid of the former eight pine species and that the abietic-type is lower.Three kind of acids in the latter two pine species and the check pine,have been found,and the abietic-type is high. Hence,this is recognized as the main mechanism of anti-pest of the pine species.