The particulate status characteristics of diesel engine particulate were studied by using thermo gravimetric analysis, scanning/transmission electron microscopy (SEM/TEM) and staged sampling particulate system methods. The variation of the composition, size distribution and microstructure of particulate with different ethanol ratios were studied. Results showed that soot accounted for about 75% of the total particulate mass. With the increase of ethanol ratios, the proportion of soluble organic fraction (SOF) increased and sulfate decreased. With the increase of ethanol ratios, the particulate of size range 0.78～1.4μm decreased and the proportion of 0.25μm increased. The distribution of particulate moved to small size. The particulate size decreased and agglomeration improved with the increase in the proportion of ethanol ratios. The microstructure of the particulate was polymerization, core-shell and disordered.