Abstract: An open CNC(computerized numerical control) system based on RTLinux for the 5-DOF(degree of freedom) parallel laser processing machine is studied,and the forward and inverse displacement models for the five degrees of freedom parallel configuration with three branches is embedded in the system.In the models,the multi-solution problem of the special displacement is solved.In the interpolating process,S-shape acceleration and deceleration control algorithm and small line segment interpolation are used.In addition,process control module is incorporated into the CNC system to adjust laser processing parameters including laser power and defocus length etc.