In order to enhance technological level of gear manufacturing comprehensively, the processing methods of precision and ultra-precision cylindrical involute gears were researched. The work principles of several gear-grindings and machining statuses of ultra-precision cylindrical involute gears were analyzed and compared. Then, machining of ultra-precision gear above quality 2(ISO1328:1997) was probed. Finally, the gear grinder Y7125 with big plan wheel provided with the advantages of streamline structure, high rigidity of transmission chain, high accuracy of gear-grinding and much room to modify was pointed. Research results show that the grinder Y7125 is probably to be a master grinder of ultra-precision cylindrical involute gear to produce ultra-precision gear from quality 2 to quality 1. The development of ultra-precision with quality 1 can enhance the gear normal and technological level of gear manufacturing.