Abstract: According to drug combination principle 26 substituted benzaldehyde/cinnamicaldehyde semicarbazones were synthesized. Twelve of which were not found in lit-erature. The structures of the title compounds were confirmed by elemental and IR, UV,¹HNMR and MS analyses. Thirteen compounds were screened in vivo against Ehrlichascites tumor cells. Four compounds (Ⅶf, Ⅶg, Ⅶh, Ⅶm )showed strong antitumoractivity. The percent increase in life span were between 46.1%～91.1%. 3- Methoxy- 4- hydroxy and 3- methoxy- 4- acetyloxy- cinnamicaldehyde selenosemicarbazonesshowed stronger activity and less toxicity with increase of life span of 76.5% (300 mg/kg)and 91.1% (60 mg/kg ), respectively. They were worthy to be studied further.