The invention provides a command and parameter generating device comprising an interpreting module, a planning module, a simulation analysis module and an optimization calculus module. The command and parameter generating method includes that the interpreting module interprets the workpiece program to produce the track coordinates of the workpiece; the planning module interpolates the trajectory coordinates and generates the path information and velocity information of the tool; the simulation analysis module analyzes the trajectory characteristics of the tool by the path information and velocity information, and gives the cutting simulation message; and the optimization calculation module generates the optimal control parameters of the corresponding block according to the trajectory characteristics of the different blocks of the workpiece and the cutting simulation quality. The device described in the present invention is an auxiliary device which can be arranged independently of the machine control system or as a subunit of the machine control system and operates in the machine control system.