Based on ultrasonic geometric acoustics principle, a circular ultrasonic transducer array was designed, where fan-shape beam ultrasonic transmitters were applied to emit ultrasonic pulses.Further, with a multi-channel synchronous data acquisition system, the whole transmission-mode ultrasound computerized tomography (UCT) device was developed.The basic principle of binary logical back projection reconstruction algorithm (BLBP) and its improvement were presented in detail, followed by experiments on a polytetrafluoroethylene (PTEF) plate and rod.The results show that the system can be used to identify the size, shape and location of objects.Comparing the images reconstructed by BLBP with given values, their errors are within 6% in the case of a single circular rod.