Abstract: During the commissioning phase of China Advanced Research Reactor (CARR）, the asynchronism was found between drive coils and control rod when the control rod drive mechanism (CRDM) taking inversion. With the aim of acquiring inversion performance of the CRDM, a CRDM inversion performance test was taken under the condition of static coolant. The result of test shows that asynchronism between drive coils and control rod is the intrinsic characteristic of magnetic suspension CRDM; the factors, such as control rod position, control rod speed and drive coil current, have limited influence on static coolant inversion performance, and the inversion performance of four groups CRDM have uniformity under static coolant condition; the distribution of electromagnetic determines that the dynamic inversion performance is better than static inversion performance.