Abstract: This paper studies the negative pressure closing liquid impact factors and boundaries, negative pressure liquid test methods resumption, the relation between negative values and closing fluid rate, negative pressure closing solution process and its extraction by the law of leaching agent penetration and negative pressure closing fluid mechanism to explore the feasibility and effects of the negative pressure liquid collection of weathered crust elution -deposited rare earth ores with in -situ leaching. The liquid collection rate and negative pressure value basically linear relationship by optimizing the liquid collection method and condition. The best pumping liquid downtime and boot time are 10 min and 50 min respectively. Three holes are pumped consecutively with negative pressure value maintaining around 2.66×10⁴ Pa or above. Some ten-thousand-tons ore block industrial tests are performed to verify optimization conditions. The ideal test results and technical and economic indexes are achieved in which the REO leaching rate is 77.5 %.