In order to find more effective radioprotector, a new radioprotectors 3,4,5-trimethoxyphenylpropenoic Acid Diethylaminoethylthiol Ester has been synthesized which is a derivative of Sinapic Acid Thioester by changing known structure of radioprotector Sinapine. The main step to synthesize this agent is involved the condensation of 3,4,5-trimethoxyphenylpropenoic Acid Chloride with diethylaminoethylthiol under base catalyst. And the ESR Spectra from Sinapic Acid Thioester derivative-dTMP and DNA with molar ratio 1:10 irradiated and recorded at 77 K and after annealing at room temperature has confirmed the long range electron transfer from Thymine moiety of dTMP to protector Thioester:,http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=42648970&type=,http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=42648987&type=,http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=42648985&type=,The ESR Spectra of Thioester-dTMP and Thioester-DNA binary systems reveal characteristics similar to that from Thioester which represent carboxylic anion radical alone. After annealing at room temperature, the ESR pattern of Thioester-dTMP binary system changed into carboxylic anion of Thioester radical ,http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=42648990&type=,http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=42648992&type=,http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=42649005&type=, alone, and no traces of ESR signal from 5-thymyl radical could be found. The new synthetic Sinapic Acid Thioester Derivative is one of new kind radioprotectors with "potential thiol" group that is different from literature known radioprotectors such as thiosulfates, phosphorothioates and thio acetic acids from them free thiols may be formed metabolically, and it is estimated to be with lower toxicity and higher protective and therapeutic effect for this new kind agent; The primary antiradiation test on mice irradiated with ,60,Co ,γ, radiation of 7.5 Gy showed the protective and therapeutic effects by enhancing an mal survival rate of 20% and 40% respectively within 30 days after irradiaradiation in the cases of protective and therapeutic administration of drug with dose of 1.5 mg/mouse (intraperitoneal injection) by comparison with the control group of mice. The Sinapic Acid Thioester Derivative is not only with the activity of radioprotection but also with the activity of reinforcement of injured organism repair processes. So far as described as above, it may be concluded that Sinapic Acid Thioester Derivatives act not only as antioxydants and radical scavengers but also act as affecting repair processes for the injured organism.,The Ms. I. R. and NMR Spectra of Sinapic Acid Thioester Devivative also have been reported.