This article describes the preamplifier of the time-of-flight detector in BES Ⅲ

including the design principle

structure feature

performance parameter and burn-in test of the preamplifier. The preamplifier takes an important role in the 25ps time resolution of the TOF electronics system; moreover the preamplifier accomplishes high bandwidth

high gain and large dynamic range. In order to eliminate the infant mortality and freak failures

which correspond to failures introduced by PCB assembly process and premature component failure of manufactured parts respectively

each preamplifier came through the burn-in test which is introduced in this paper. The preamplifier was verified by the BES Ⅲ headquarters.