The radial runout of spindle shaft in machining, which causes errors such as roundness and roughness, is undesirable by measuring mandrel directly due to the machining state and eccentric error between rotational axis and the mandrel.A dynamic adjustment and laser measurement method was present based on the thesis that the cochannel part in lathe’〖KG-*2〗s radial runout could not influence the surface quality and roundness.A simple precision adjustment and measuring device was developed.By a simple connecting mechanism with the turned workpiece, a standard mandrel was firmly sticked to a smooth glass by the huge force of a magnet.Then, adjusting the mandrel and measuring the rotary data, the position of rotary axis could be obtained.Finally,a Vtype filter and Grubbs filter were designed to remove the cochannel part and abnormal error in lathe’〖KG-*2〗s radial runout.The experimental results show that the measure data is approximate with the roundness of the workpiece, and positively related to the cutting dosage.