Nowadays marine electromagnetic method is a geophysical method which can effectively explore natural gas hydrate (NGH) resources. This method acquires seafloor structure and distribution laws of mineral resources by transmitting high-power electromagnetic waves to the seafloor, and its detection depth relies on intensity of transmitted electromagnetic waves. At present, marine electromagnetic transmitter is inappropriate for transmission of high-power electromagnetic waves, and therefore, a novel DC/DC controlled-source circuit formed by input-series and output-parallel ZVZCS DC/DC controlled-source circuit units was proposed in this paper, and thus transformation of high-voltage and high-power electric energy was realized by using switching devices with low rated voltage and rated current. Common duty ratio control is adopted to construct small-signal mathematical model of cascading-combination ZVZCS DC/DC controlled-source circuit, influences of parameters on voltage balance at input side and current balance at output side are analyzed. Simulation and experimental results verify that the proposed circuit has favorable voltage and current sharing effect and could satisfy deep exploration requirements of marine electromagnetic transmitter with high transmission voltage.