Abstract: In order to provide experiences for the construction of mixed forest, we conducted an investigation on a 12yearold Robinia pseudoacacia and Populus mixed forest based on 3 typical sample plots. Results showed that the volume of per hectare can be enhanced up to 35.1 % higher in the Populus and R. pseudoacacia mixed forest than that in monospecific R. pseudoacacia forest at least. The rate of suppressed tree of R. pseudoacacia in the sample plot with high dominance of Populus was as high as 64.1 %. The competition intensity of R. pseudoacacia in the sample plot with high dominance of Populus was 188 % higher than that of with low dominance of Populus on average. Moreover, the interspecific competition of R . pseudoacacia accounted for 81.9 % in the sample plot with high dominance of Populus. However, it was only 35.5 % in that with low dominance of Populus. In addition, the growth and competition situation was different although Populus important value was similar. The above results suggest that the Populus and R. pseudoacacia mixed forest growth modeling based on their spatial competition disciplinarian should be studied for healthier mixed forests.