Abstract: Cleanliness has important effect on the mechanical properties of ship plate steel. The total oxygen,nitrogen,and inclusions in DH36 ship plate steel produced by BOF-LF-RH-CC processes were studied by systematically sampling in each step in steel production and analyzing the shape,size,quantity and components of inclusions by multiple analyzing techniques. The results indicate that the cleanliness of DH36 steel produced with BOF-LF-RH-CC processes is high. The average total oxygen content of the slab is 17.0×10^-6,the N content is 29.0×10^-6,and the quantity of micro inclusions in the slab is 6.8 mm^-2. They are mostly spherical complex oxides and sulfides with the size less than 5 μm in the slab,which meet the requirements of high-level ship plate steel.