In this paper, we describe ARMOR, an Agile keRnel coMpOnent Runtime which seeks to greatly enhance operating system reliability and performance at the same time. ARMOR is made up of AKE, Agile Kernel Engine which is implemented in kernel, and system servers which are user processes. In ARMOR, the kernel functions are encapsulated through component and can be loaded both into kernel address space for performance and into system server's user address space for reliability at runtime. ARMOR isolates kernel components through loading them into system server's user address space, where hardware and software prevent them from corrupting the kernel.To prove the feasibility of our approach, we implemented ARMOR in Linux operating system and some experiments are given to evaluate our work.