An external-pressed polysulfone hollow fiber UF membrane, was made by phase inversion method. The cutoff molecular weight was 6000. The water permeation rate of this membrane module (psi 90 x 500 mm) is more than 150 L/hr.atm. The operating results show that the elimination of bacterial endotoxins by this membrane has reached the national standard in pharmacopoeia, and this technology is worthy to be extended over to medical industry. In addition, the essence of pyreotogen, the quantification units and measure methods for pyreotogen, and the operating conditions of UF device in the process of eliminating pyreotogen are introduced. Some critical points in operation was discussed.