Cone enveloping cylindrical worm in traction machine as instance, theoretical analysis on cylindrical worm transmission has been theoretically analyzed, and efficiency test and load capability test of traction machine with YJ240 cylindrical worm have been done on open power gear experimental instrument. According to the experimental data, it indicates cylindrical worm have some weaknesses on load capability, efficiency, adjustment possibility of tooth backlash and so on. Therefore, on purpose of improving integral performance of traction machine, face worm with variable tooth thickness may be used as primary drive mechanism in traction machine instead of cylindrical worm.