In this study, a co-processor for six-legged robot is designed and implemented. Kinematic calculations are complicated and many times we need a separate computation unit when we need high accuracy and precision. Co-processor usage is widespread for decreasing the load on the main computation unit. The co-processor designed in this study is specialized for servo motors controlled via serial port. The co-processor takes and sends the command via serial port. It can compute the joint angels of an 18 degree of freedom (DOF) six-legged robot in real time. The experimental studies are made by computer and on a robot prototype and taken good results.