Abstract: Based on the specific requirements of battery charging, a three-phase balanced eharg-ing circuit controlled with one thyristor is proposed. This circuit is free from the defects existing in general single-or three-phase thyristor charging circuit but has the abvantages of the both. It is capable of achievement of three-phase synchronous re-gulation throughout the whole range by a simple way. Thus, it is different from the traditional method. there is no need to adopt multi-thyristor in three-phase balanced network to balance and synchronize the regulated D.C. output voltage. The purpose of this paper is to present a new practical circuit which is not only simple, economic, but also able to be three-phase balanced in voltage regulation, thus providing a good design of charging equiplent controlled with one thyristor.