To investigate the chemical constituents of the roots of Andrographis paniculata, 28 compounds were isolated and identified from the 80% ethanol extract.  There are 20 flavonoids: 5, 5'-dihydroxy-7, 8, 2'- trimetroxyflavone (1), 5-hydroxy-7, 8, 2', 6'-tetramethoxyflavone (2), 5, 3'-dihydroxy-7, 8, 4'-trimethoxyflavone (3), 2'-hydroxy-5, 7, 8-trimethoxyflavone (4), 5-hydroxy-7, 8, 2', 3', 4'-pentamethoxyflavone (6), wightin (7), 5, 2', 6'-trihydroxy-7-methoxyflavone 2'-O-β-D-glucopyranoside (8), 5, 7, 8, 2'-tetramethoxyflavone (10), 5-hydroxy- 7, 8-dimethoxyflavanone (11), 5-hydroxy-7, 8-dimethoxyflavone (12), 5, 2'-dihydroxy-7, 8-dimethoxyflavone (13), 5-hydroxy-7, 8, 2', 5'-tetramethoxyflavone (14), 5-hydroxy-7, 8, 2', 3'-tetramethoxyflavone (15), 5-hydroxy- 7, 8, 2'-trimethoxyflavone (16), 5, 4'-dihydroxy-7, 8, 2', 3'-tetramethoxyflavone (17), dihydroneobaicalein (18), andrographidine A (19), andrographidine B (20), andrographidine C (21) and 5, 2'-dihydroxy-7, 8-dimethoxyflavone 2'-O-β-D-glucopyranoside (22); three diterpenoids: andrograpanin (23), neoandrographolide (24) and andrographolide (25); two phenylpropanoids: trans-cinnamic acid (26) and 4-hydroxy-2-methoxycinnamaldehyde (5); and oleanolic acid (9), β-sitosterol (27) and β-daucosterol (28).  Compound 1 is a new flavone, compound 4 is a new natural product, compounds 2, 3 and 5 were isolated from the Androggraphis genus for the first time and compounds 6−9 were isolated from this plant for the first time.