Abstract: This paper describes the isolation of two tropane alkaloids (alkaloid Ⅰ and Ⅱ) from Physochlaina physaloides. On the basis of spectroscopic analyses (IR UV MS NMR) and the physico-chemical constants, alkaloids Ⅰ and Ⅱ were identified as hyoscyamine and anisodamine respectively. The total alkaloid contained mainly these two alkaloids. Due to the high alkaloid content and simple isolation procedures, this plant may serve as a good source to obtain these two important tropane alkaloids.It was found that anisodamine hydrobromide had two different melting points (159～163℃ and 176～178℃) representing two crystal forms. Their infra-red spectra were also different. The two forms of the crystals were able to interchange from one form to the other, the higher melting point crystal form being relatively more stable. No difference in the pharmacological action and toxicity between these two crystal forms was observed. Consequently, there is an polymorphism in this case.