The invention relates to an automatic lapping and 
polishing system for a complex surface of a compliant control-based 
robot and a 
machining method. The automatic lapping and 
polishing system comprises an 
industrial robot, a worktable, a 
force sensor, a flexible lapping and 
polishing cutter, a 
signal conversion 
amplifier, a computer and a 
robot controller; the method comprises the following steps: performing 
machining trace planning before lapping and polishing a complex surface workpiece to obtain cutter contact point trace of the lapping and polishing cutter to obtain a surface 
machining cutter location point trace; converting the surface machining 
cutter location point trace into a code format program file which can be identified by the 
robot controller, and inputting the code format program file into the 
robot controller; positioning and clamping the workpiece to complete coordinate labeling and unification of a process 
system; and driving the robot to move according to a machining trace planning program file to drive the lapping and polishing cutter arranged on an end executor of the robot to perform contact machining on a 
machined surface. According to the automatic lapping and polishing system and the machining method disclosed by the invention, manual operation at a finish machining stage of the complex surface workpiece, especially a large-sized complex surface workpiece, can be replaced; labor strength and machining cost are reduced; and quality stability and quality consistency of a machined molded surface are increased.