Abstract: The affecting factors on the coaxiality measurement results were analyzed，including coaxiality bar material，test load，calibration method，assembly mode，loading rate，mechanical eccentricity，etc.The results indicated that among three measurement methods of coaxiality，the strain gage method was best，followed by extensometer method and geometric method.The influence sequence of each factor ranked as:mechanical eccentricity，assembly mode，coaxiality bar material，calibration method，loading rate.The coaxiality was increased with an increase in mechanical eccentricity，elastic modulus of coaxiality bar material and loading rate，while decreased with the rise of test load.The influencing order of assembly mode on coaxiality was the thread fixture，round bar fixture and the fixture with universal structure.

Key words: Coaxiality, Materials science, Eccentricity