A series of novel 2-amino-4-phenylthiazole derivatives were designed and synthesized, furthermore, their inhibition effect on acetylcholinesterase were investigated. 2-Amino-4-phenylthiazoles were prepared from alpha-bromoacetophenones by Hantzsch reaction, acylation reaction and substitution reaction. Moreover, their bioactivities as AChE inhibitors in vitro were measured with Ellman spectrophotometry. The results showed that most of them had a certain inhibition activity on AChE, and the compound 8a was the best of them. The IC50 of 8a to AChE is 3.54 micromol x L(-1), and the value was better than that of rivastigmine. 2-Amino-4-phenylthiazole derivatives showed a certain bioactivity in vitro, which were worth further investigation.