Manmade unavailable action for economy is the major reason thatcauses sever soil loss in YiMon mountainous region. The principal harmand destruction of soil loss to ecological environment and economy construction is as follows, that land deteriorates, production yield decreases,deposition of river and reservior or pond affects the bonefit of engineering, ecological environment worsens, natural disasters occur frequently.To periorm soil and water conservation of YiMon mountainous regionwell should be in accordence with the ecological economy princiles, thatthe first is to uphold entirty of the system, taking the small watershedas a unit to harness soil loss of YiMon mountainous region comprehensively, the second is to insist on the principle of structure, regulating agricultural arrangement rationally, and the third is to persevere the principle of correlation, making prevention and protection when working onharness.