Abstract: The relationship between amino acid contents of host trees and Kerria lacca was studied. The results were as follow:1.Amino acid contents among 7 different host trees species and branches hosted or not hosted by Kerria lacca were different. Principal components showed that the amino acid contents of 14 different branches could be divided into 3 groups.2.When the amino acid contents of hosted branch were close to the amino acid contents of annual kusum branch, the thickness of raw lac was thicker; when the amino acid contents of hosted branch were departed from that of annual kusum branch,Kerria lacca had higher mortality and fecundity; the relationship between amino acid contents of hosted branch and the amount lac secreted by per lac insect was complicated. 3.Kerria lacca hosting had some influence on amino acid contents of branch. The entire amino acid contents of hosted branch decreased by 35% comparing to that of control kusum branch, the contents of aspartic acid, threonine, serine, glycine, alanine, isolleucine, tyrosine, valine, leucine, phenylalanine and methionine decreased in different degree. But after hosted by Kerria lacca,the contents of histidine, lysine, arginine and tryptophan were higher than that of control branch. The contents of some kinds amino acid of hosted branch also increased or decreased in other species host trees.