In this paper, the contents of free amino acids in Sophora alpecuroides Linn was analysed. The total content of the sixteen kinds of free amin acids was 194.52 μg/100mg. The content of glutamic acid was the highest which was 47.68 μg/100mg and methionine content was the lowest which only amout 0.20 μg/100mg. There were 7 kinds of essential amino acids whose total content was 17.33% in Sophora alopecuroides Linn .