Factors that affect the corn densification contained pressure, heating temperature, moisture content and etc., and microstructure of briquette also has a major impact on the macroscopic properties. The microstructure and binding mode of material particles inside briquette were observed with electron stereoscopic microscope, the relationship between molding process parameters and forming microstructure were studied from the microscopic view. The results showed that particles in corn straw briquette were mainly combined in two forms—mechanical mosaic and natural adhesive bonding. Under the condition of pressure 60~90MPa, material temperature 75~100 ℃, moisture content 8%~16%, internal particles of briquette were combined closely, with obvious mechanical enchase effect, corresponding to get physical quality and mechanics with good performance. 