Based on the demand for detection of wear debris in lubricating oil in the outdoor environment,several kinds of particle detection technologies were analyzed,and a kind of portable image detector for detection of wear debris in lubricating oil was designed,which combined magnetic adsorption and CCD sensor to obtain the wear particle images.In order to obtain the optimal magnetic adsorption effect in the limited instrument structure space,and make as many abrasive particles as possible adsorb to the focal plane of the CCD sensor,the structure parameters of the magnetic pole,including the area,width and thickness of the magnetic pole,the length,thickness of the excitation coil and its relative position to the magnetic pole were analyzed,and the optimal magnetic pole size was obtained.The magnetic intensity change curve in sedimentary region was analyzed.It is found that the magnetic intensity is increasing from the ring core to the pole until it reaches the peak at the interface between the core and the air,then quickly declines,and then rises rapidly after reaching the center of sedimentary area,forming an Mshaped curve.