Objective: To study the changes of andrographolides in the drying process of the extract of Andrographis paniculata Nees. Methods: HPLC method was applied to analyze andrographolide and 14 deoxy 11, 12 didehydroandrographolide in the process. Results: The content of andrographolide descended rapidly in the whole drying process, while the content of 14 deoxy 11, 12 didehydroandrographolide ascended at first 12 hours, declined in content was slowly to follow. Conclusion: Baking temperature is not the only main factor to stimulate the transformation of andrographolide and 14 deoxy 11, 12 didehydroandrographolide.