To determine the reasonable sampling oil location for online Visual Ferrograph (OLVF),the distribution of wear debris in the CA6DL engine oil pan was simulated based on the FLUENT.The results of numerical simulation of solidliquid two phase flow show that the distribution of wear debris in the oil pan is uneven,and the location in the top of suction filter can be used as ideal sampling point for OLVF.According to the parameters of CA6DL engine lubrication system,the engine lubrication system simulation test rig was developed,and experiment studying on the online sampling of OLVF was carried out.The experimental results show that the abrasive particles tend to gather in the top of suction filter during the circulating of lubricating oil.In this position,it is sensitive to the change of wear debris concentration,and the large wear debris concentration is high and the persistence time is long.The experimental result verify that the sampling position determined by numerical simulation can be used as the best sampling area for OLVF monitoring of CA6DL engine.