Abstract:The effects of mixed rare - earth elements of La and Ce on some physiological characteristics of Robinia pseudoaeacio one - year‘ s seedlings (tree seedling, cuttings, root - cuttings) were studied. The results show that spraying the rare - earth elements solution in 700mg / kg on the leaves of R. pseudoaeacio, the net photosynthetic rate was increased by 33.8%- 40.3%, the content of chlorophyll was increased by 22.3%-33.1%, the water applying efficiency would be increased by 1 0.2%- 14.0%. The total nitrogen, phosphate. And potassium content of the leaves can be increased respectively by 3 1 .7%-46. 1%, 22.0%-32.7% and 42.9%- 55.6%.