Abstract: We analyze the mechanism of abrasion, plugging burst pipes of the "L" type filling pipelines. We can know that the impact of filling pulp free-fall is the key factor of pipeline abrasion; pipe break accident easily occurs at the interface of air and mortar; tube rupture easily occurs at the junction of the vertical tube and horizontal tube. Based on this, we proposed technical optimization program of "L" type filling pipe and elaborated principle of each part.