Abstract: Aiming at the defects which exist in present yarn linear density test device, an automatic test device about yarn linear density and weight eveness was developed. This device included electronic balance, spring linear pressure, electronic calculation length , frequency conversion winding and controller. Test length and advanced tension were set refering to GB/T 4743 2009, test procedures and methods about linear density and weight eveness were introduced using this device. A linear density contrast test was done taking T/R65/35 bobbin yarns as example, practice showed: its accuracy of the test results was 99.7%, while the test results accuracy using traditional device was only 95%. and test process was convenient, yarn was continuous without waste yarn, it also had smaller volume, so it had higher application and promotion value.

Key words: yarn , linear density , weight eveness , test device