Disclosed are uses of a Pulsatilla saponin compound B4 or a pharmaceutically acceptable salt thereof in preparing a drug for treating viral and/or bacterial diseases. The Pulsatilla saponin compound B4 disclosed by the invention shows a strong biological activity, and efficiently treats endometritis, footrot, feline parvovirus, canine parvovirus, canine distemper, canine kidney failure, and canine acute nephritis. (I)