OBJECTIVE： To study the chemical constituents of Clinacanthus nutans branches and leaves and its anti-tumor activity in vitro. METHODS： Varied chromatographic techniques were conducted to separate and purify the ethyl acetate and butanol parts of 95％ ethanol extracts of C. nutans， the chemical structures were analyzed and identified according to physicochemical property and spectral data. MTT method was used to determine the inhibitory activity of identified compounds on human liver cancer BEL-7402 cell lines， gastric cancer SGC-7901 cell lines and chronic myelogenous leukemia K562 cell lines in vitro. RESULTS： Eight compounds isolated from C. nutans branches and leaves were identified as lupeol （1）， methyl p-coumarate （2）， 1-O-acyl-3- O-（β-D-galactopyranosyl）-sn-glycerol （3）， （6R， 10R）-6，10，14-trimethyl-2-pentadecanone （4）， 1， 2-benzenedicarboxylic acid bis （2-ethylhexyl） ester （5）， methyl α-D-galactopyranoside （6）， methyl β-D-glucopyranoside （7）， 9-hydroxy-megastigma-4，7-dien-3-one-9-O-β-D-glucopyranoside （8）. Compound 1 had weak growth inhibition effect on human liver cancer BEL-7402 cell （half inhibitory concentration was 42.5 μmol/L）， the other 7 compounds had not been found to inhibit the above 3 tumor cell lines. CONCLUSIONS： Compounds 2-8 are all isolated from C. nutans branches and leaves for the first time， while lupeol has weak growth inhibition effect on human liver cancer BEL-7402 cell. The study has laid the foundation for the quality evaluation of C. nutans.