The invention provides a method for extremely fine 
grinding and finishing the surface of a 
cam of an 
internal combustion engine camshaft through electrochemical composite oilstone with reverse pulses. The method has the following advantages that firstly, the surface of the 
cam can be directly finished to Ra0.1 
micrometer or lower through one step after being coarsely ground, so that mirror finishing is achieved; secondly, compared with 
grinding at the same roughness level, the productivity can be improved by three times to five times or more, and finishing efficiency is quite high; thirdly, in the finishing process, no 
grinding force or grinding heat is generated, so that the 
surface layer is free of metallographic structure changes, 
work hardening and stress condition changes, and the finished 
surface layer is high in quality; fourthly, passive film on the 
metal surface is mainly removed through the oilstone, and therefore loss of the oilstone is much smaller than loss caused by ultra-fine 
machining; fifthly, sediments and microscopic peaks on the surface of an 
electrode are dissolved through the reverse pulses, the 
electrode is finished, and the shape of the 
electrode is kept; sixthly, the process device is simple and is convenient to operate and maintain.