A method for producingFallopia Japonicaextract that inhibits CXCR4 of leukocytes is disclosed. The method includes the following steps. A root ofFallopia Japonicais extracted with methanol to yield a crude methanol extract. And then, the methanol in the crude methanol extract solution is removed to produce a crude extract that contains emodin and physcion.本發明揭露一種抑制白血球之CXC趨化素受器4型的虎杖萃取物之製造方法,包含下列步驟。首先,利用甲醇萃取虎杖根部,以獲得粗甲醇萃取液。接著,去除粗甲醇萃取液中的甲醇,得到一粗萃取物,其中此粗萃取物包括大黃素(emodin)及大黄素甲醚(Physcion)。