Abstract: It is now accepted that there is an integral interaction between plants and their environments and that species_specific alkaloids, as plant chemical defensive weapons and signal compounds, are key players in this interaction. In the past three decades, metabolic biology of alkaloids, with respect to biosynthetic and storage positions, transport pathway, regulatory factors, biosynthetic pathway and key enzymes as well as its encoded genes, have achieved much and this paper attempts to give a review on this field, followed by some suggestion about the existing questions and perspectives.