Abstract: In this study, we chose Amorphophallus albus which is a Plant Species with Extremely Small Populations (PSESP) endemic to dry-hot valley of Jinsha River to observe the difference of calcium oxalate crystals among different parts of A. albus inflorescence (spathe, appendix, androecium, staminode, gynoecium) under microscope. Additionally, we used methanol extract of each part of the inflorescenceto explore the poison effect to rove beetle Atheta sp. which are the main pollinators of A. albus. The results showed that the highest content of calcium oxalate crystals was found in gynoecium of A. albus, with 188.4 calcium oxalate crystals per 1 250 μm² field of vision. It was supposed that high concentration of calcium oxalate crystals in gynoecium was to protect the ovule. The lowest content of calcium oxalate crystals was in staminode, with an average of 11.9 calcium oxalate crystals. The results of methanol extracts from different parts of inflorescence showed that only gynoecium extract could kill Atheta sp. rapidly (< 14.5 s), while the extracts from other parts could not kill the rove beetle within 60 s. We infer that high concentration of calcium oxalate crystals or other coexisting toxic substances have toxic effects on the rove beetle.