Based on the main factors resulting in NC milling errors of piezo jacquard guide bar used on 230″ warp knitting machine,the NC milling techniques of long and thin workpieces affecting machining quality in the manufacture process,such as machining path,cutting strategy,fixing workpieces and cutting parameters were analyzed.The techniques and technological ways of controlling deformation and improving milling precision and surface quality were proposed.The results showed that the milling precision and the surface quality requirement was reached because of the milling technique of piezo jacquard guide bar.