Control valve (actuator) is the frequently moving terminal Instrument of the control system. To avoid the leaking of the actuator, there is packing at the moving parts. However, the friction caused by the packing can do harm to the control of the system. The washing effect of the media, high temperature, high pressure, frequent movement and other effects can result in the leaking of the packing and the deformation of the valve stem, which causes the change of the friction. In this paper, published in Sensors & Transducers, Vol. 177, Issue 8, August 2014, it’s theoretically analyzed the relationship of the friction of the packing and the static performance of the control valve, and offered a method to check the quality of the moving parts by attaching a strain gage (strain rosette) to the empty part of the valve stem. This method has been demonstrated via experiment and a method to do error detection is provided at last. Paper published by http://www.sensorsportal.com/.