The invention discloses a CLCL resonant type DC(Direct Current)/DC converter of fundamental frequency-frequency doubling dual operating modalities, belongs to the technical field of DC/DC conversion,and solves the problem that an existing CLCL half-bridge high-order resonant type DC/DC converter has a narrow input voltage range. The converter is characterized in that a direct current voltage conversion unit is connected with a direct current power supply for generating a first square-wave voltage signal when the converter works under a fundamental frequency modality and for generating a second square-wave voltage signal when the converter works under a frequency doubling modality; the frequencies of two square-wave voltage signals are equal, duty ratios are both 0.5, the amplitude of thesecond square-wave voltage signal is half of the first square-wave voltage signal; the voltage input side and the voltage output side of a CLCL resonant unit are independently in cascade connection with the voltage output side of the direct current voltage conversion unit and a transformer primary winding; and an alternating current voltage signal output by the transformer primary winding is rectified through a rectification unit and filtered through a filtering unit in sequence to be loaded to two ends of a load.