  The Erd\H{o}s-Simonovits stability theorem is one of the most widely used
theorems in extremal graph theory. We obtain an Erd\H{o}s-Simonovits type
stability theorem in multi-partite graphs. Different from the
Erd\H{o}s-Simonovits stability theorem, our stability theorem in multi-partite
graphs says that if the number of edges of an $H$-free graph $G$ is close to
the extremal graphs for $H$, then $G$ has a well-defined structure but may be
far away to the extremal graphs for $H$. As an application, we solve a
conjecture posed by Han and Zhao concerning the maximum number of edges in
multi-partite graphs which does not contain vertex-disjoint copies of a clique
