CAN bus will be increasingly used in wide range of applications for its superiority, but it couldn’t communicate with computer directly. The article describes the design of RS232 and CAN bus protocol converter depending on PIC Microcontroller, which solves the problem that CAN networks can not directly communicate with PC. At present, single-chip microcomputer of 51 series with CAN controller SJA1000 are widely used in domestic. Considering cost and converter size, the paper will talk about PIC18F2580 with integrated CAN microcontroller designed for RS232 and CAN protocol converters to facilitate the direct communication between computers and CAN bus.