Abstract: To study test stability of Primer aQura, the card sliver produced in two different experiments (12 plans in each experiment) was tested by aQura. By a statistic analysis of the test results, the number of test times that can get a reliable test result of test parameters and CV values of 30 test results of each experiment plan were obtained. It is concluded that the parameters about fiber length are repeatable when they are tested for 10 times or above. the parameters of nep with cotton shell (SCN) size, total nep number and fiber nep number are also repeatable when they are tested for 10 times or above. The parameter of SCN number is repeatable only when it is tested for 19 times or above.