The invention relates to a semiconductor element testing system with rotary test arms. A test site allowing a plurality of testing instruments to be electrically coupled to the testing system comprises a conveying device provided a plurality of bearing seats for bearing objects to be measured, a first test seat positioned in the test site and provided with at least one test position, a second test seat positioned in the test site and provided with at least one test position, a first test arm and a second test arm. The first test arm and the second test arm can run between the conveying device, the first test seat and the second test seat in the way of carrying the objects to the measured, so that two different measurements can be carried out on the same machine through the rotary test arms, or the two test seats are only used for measurement; and as the two test seats can work simultaneously, the time spent during the whole measurement can be reduced, and the test speed can be increased.