Abstract: After our discovery of promoting growth effects of quinolizidine alkaloids from Sophora alopecuroides in poplar trees,the tree trunk injection formulations containing mainly the quinolizidine alkaloids from S.alopecuroides promoting breast diameter growth in poplar trees have been developed.The formulations contain also amino acids from plants,mineral salts like N,P,K salts,plant hormones,microelements like Cu,Mg,Zn,Co,Mo,B,Fe et cetera,for which the national invention patent has been applied.In Shandong,Jiangsu and Anhui provinces the trunk injection formulations were tested on several tree ages of popular varieties in poplar forests,and the net breast diameter growth was 63.8% to 223% higher than that of control in a period of about two months in summer and fall.Tests of dosage of total alkaloids of S.alopecuroides in one hundred times more than that in the injection formulation shown that the height growth of treated trees was not affected,the breast diameter growth of the treated tree was significantly increased.The results indicated that within the testing dosage the alkaloids had no toxicity on poplar tree.The tests of injecting the alkaloid formulation and synthetic pesticide,omethoate respectively shown that the recovery rate of the injected holes in the alkaloid formulation group was significantly greater than that in the omethoate group and also that in the control group.The results of tests of application methods with the trunk injection formulations shown that though differences in effects for the formulations in promoting breast diameter growth existed,effects of promoting breast diameter growth in injecting method were always better than that of spraying.