Feasibility study on the application of direct microfiltration (DMF) in the pre-treatment of seawater reverse osmosis (SWRO) in naval vessels was performed by using domestic polyvinylidene fluoride (PVDF) hollow fibre membrane. High turbidity raw seawater was treated under the following conditions: DMF processing for 20 min, double-wash with water and compressed air for 30 sec, backwash of filtrated water for 30 sec, and filthy water discharge for 5 sec. Experimental results showed that silt density index (SDI) of filtrated water after DMF processing lowered to 2.9 or less, turbidity decreased to 0.9 NTU. Microfiltrtation membrane had a good anti-pollution feature. When the trans-membrane pressure (TMP) of the DMF processing system was higher than 37 kPa, back purging with sodium hypochlorite and hydrochloric acid could restore the TMP to a lower level. The DMF pre-treatment system had the features of being compact, easy for operation and stable output of quality filtrated water, which could meet the demands specified in related standards concerning development of shipboard equipment. We believe that this DMF system could be used in the pre-treatment of seawater with SWRO aboard naval vessels.