μC/OS-II is an open source kernel and has a preemptive scheduling strategy based priority, can only create 64 tasks, With the increasing development of embedded system, the current problem of the majority which must be solved is the more complex tasking support. So from studying of the μC/OS-II kernel structure and scheduling policy, a new task extended method is proposed in this paper, and form rewritten μC/OS-II kernel, this paper increases number of tasks to 128. It increases the application areas of μC/OS-II and improves its applicability.