Abstract: The software and hardware design of embedded input and output system based on ARM9 and CPLD was introduced. The system adopted LCD, touch screen, ethernet, serial and USB control interfaces taking the industrial grade EP9315 as the core, and designed input and output model taking MAX2_EPM240 as the core. This system has many advantages such as low-cost, stable running, strong universality, and especially can replace PLC in many industrial fields. Key words: embedded operating system; driver; Windows CE; EP9315; CPLD