In this paper, we study the irreducible highest weight module
L(Λ
0) of affine Lie algebra
![](http://xblk.ecnu.edu.cn/UserFiles/Image/20180303(2).jpg)
. Since the three-dimensional simple algebra sl
2 is regarded as a Lie subalgebra of
![](http://xblk.ecnu.edu.cn/UserFiles/Image/20180303(2).jpg)
,
L(Λ
0) naturally becomes a sl
2-module. We present the irreducible decomposition of
L(Λ
0) as a sl
2-module.