A　growing　body　of　research　suggests　that　inhibition　of　autophagy　may　be　a　novel　means　of　treating　cancer　and　suppressing　drug　resistance.　Therefore,　a　series　of　drugs　derived　from　the　Erythrina　crista-galli　Linn　were　screened　in　this　study.　Among　them,　the　pterocarpan　erythrabyssin　II　(EL-19)　is　a　potent　late-stage　autophagy　inhibitor,　which　could　effectively　block　the　fusion　of　autophagosome　and　lysosome,　leading　to　the　accumulation　of　autophagic　substrates　in　both　ovarian　cancer　A2780　and　A2780/DDP　cells.　EL-19　did　not　impair　the　lysosomal　pH　and　lysosomal　enzyme　activity.　In　addition,　cell　studies,　and　organoid　experiments　showed　that　EL-19　inhibited　the　value　addition　of　A2780　and　A2780/DDP　cells,　suppressed　ovarian　cancer　organoid　activity　and　induced　apoptosis,　and　blocked　cisplatin-induced　protective　autophagy　in　A2780/DDP　cells.　Combination　therapy　with　DDP　superior　anti-tumor　outcomes　compared　to　monotherapies　in　animal　models.　In　summary,　EL-19　may　be　developed　as　an　anticancer　agent　by　blocking　chemotherapy-induced　protective　autophagy.