This engineering project was conducted to study of factor that affects the densified biomass from maize residues to expansion. And durability of cylindrical biomass after compression and with diameter 9 mm. And control of initial weight constant 2 g. The maize residues are corn cob, corn stalk and corn husk (The moisture of about (8%, 14% and 12% respectively) wb.).The particles of maize residues with 2 sizes were 0.00 to 0.85 and 0.85 to 1.18 mm. The pressures used to compression have 3 levels were 150, 200, and 250 MPa. And temperatures used to test have 3 levels were room temperature, 60 and 80 °C. The expansion can be measured from the diameter and length after instant compression, 1 hour after compression and every day to 5 days. The durability can be measured by pellets durability tester, rotates at 50 rpm for 10 minutes after 5 days with a compression. Found that the expansion and durability of biomass after compression is a direct variation with the particle of maize residues before compression. But inversely variation to the pressure and temperature used to compression. Recommendations for densified biomass from maize residues are. Should the reduction of particle were size 0.00 to 0.85 mm. The pressure and temperature used to compressive is 250 MPa and 80 °C respectively.