The invention discloses a noise reduction and sound insulation board for a gear room cover. The noise reduction and sound insulation board for the gear room cover is a plastic part formed by monoblock casting and particularly comprises a top plate and a buckle, wherein the bottom surface of the top plate is provided with a peripheral sealing groove for placing a sealing ring; the buckle is a ring-shaped buckle extending downwards along the bottom surface of the top plate; the tail end of the buckle has a buckle inclination angle which takes a guide effect; a plurality of fractures running through the inner and outer surfaces are formed in the peripheral side of the buckle. The noise reduction and sound insulation board for the gear room cover has a simple and reasonable structure, adopts the high damping plastic part formed by monoblock casting, is matched with the O-shaped sealing ring and is applied to the noise centralized position inside the gear room cover of an engine so as to effectively reduce vibration and noise of the gear room cover and a complete machine and weaken harmful effects brought by noise and vibration.