Five hasubanan type alkaloids have been isolated from the stem and root of Stephania Tonga L. (Menispermaoeae) collected in Hainan island. Two of them, named longaninine (longanine) and longanone, are new alkaloids. Their structures are proved to be 2 and 3 respectively with the aid of spectral analyses and ohemioal transformations. The three other alkaloids have been identified as stephaboline (1), stephabyssine (4) and prostephabyssine (6), respectively.