The bag bottom is sewn by stacking three layers of thick woven fabric of the same specification. Compared with ordinary single-layer bottoms, its impact and puncture resistance are multiplied. When materials are poured from several meters height during filling, the bottom will not be broken through to cause leakage. The full-circle reinforcement at the joint between bottom cloth and bag body avoids seam tearing. The whole bag adopts standard thickened wear-resistant fabric, balancing cost performance and bottom protection, specially designed to solve the common problem of bottom rupture during high-altitude feeding.