This paper addresses the optimal design of leakage inductance of the high-frequency transformer in dual active bidirectional converter stages of transformerless cascaded bidirectional converters. By analyzing the realization condition of zero-voltage-switching and the method to reduce reactive power under controlling of single phase shifting control strategy, the optimized circuit parameters are selected. An experimental prototype of transformerless cascaded bidirectional converters of two cascaded H-bridge in both rectifier stages is built at the rated power of 1 kW. The results of the test testify that the optimized circuit parameters indeed reduce the reactive power and increase the efficiency of the converter.