Abstract: Let $G$ be a connected reductive algebraic group over an algebraically closed field $k$ of prime characteristic $p$, and $\mathfrak{g}=\mathrm{Lie}(G)$. This paper studied the cohomology of the reductive Lie algebra $\mathfrak{g}$ with $p$-character $\chi$ of standard Levi form. When the highest weight of baby Verma module is $p$-regular, the necessary and sufficient condition for the Ext groups between baby Verma module and twist baby Verma module being non-split was gotten.

Key words: standard Levi-form, baby Verma modules, cohomology