The Goniothalamus genus have been used in folk medicine for cancer,tumor,treatments.However, G. yunnanensis,one of the species Goniothalamus,its chemical constituents and potential antitumor activities has not been reported;the aim of this paper was to investigate the chemical constituents and antitumor activities of  G. yunnanensis,as a result,nineteen compounds involved alkaloids,styryl lactones,flavonoids and triterpenes were isolated and purified from 90% ethanol extract of twigs of G. yunnanensis by using various chromatographic techniques such as silica gel,Sephadex LH-20 and semi-preparative liquid phase HPLC.Their structures were identified by modern spectroscopic methods and named as aristolactam AII (1),enterocarpam II (2),aristolactam AIIIa (3),aristolactam BII (4),griffithinam (5),piperolactam B (6),lysicamine (7),N-p-coumaroyltyramine (8),marcanine B (9),9-deoxygoniopypyrone (10),goniofufurone (11),goniothalamin (12),pinocembrin (13), β-sitosterol (14),pureonebio (15),diethyl disulfoxide (16),stigmasterol-3-O-β-D-glycopyranoside (17),cheliensisamine (18),and ursolic acid (19).All the compounds were isolated from G. yunnanensis for the first time.Moreover,isolated nine compounds from  G. yunnanensis were screened for antitumor activity by SRB method in vitro.The evaluation results of anti-tumor activity showed that the styryl lactone compound 12 shown the most obvious inhibitory effect on the proliferation of HCC1806,HCT116,and Hela tumor cells at the concentration of 50 μM with IC₅₀ 5.2±0.7,3.1±0.5 and 10.5±1.0 μM,respectively.