A structure for lowering linear polarization laser pulse repetition frequency and improving pulse energy comprises a linear polarization pulse laser source, a high-speed light polarization conversion device and a laser pulse delay light path, wherein the linear polarization pulse laser source is used for emitting pulse lasers of linear polarization; the high-speed light polarization conversion device is located on a light path output by the linear polarization pulse laser source and used for selecting polarization rotating laser pulse sequences in different periods; the laser pulse delay light path is located on a light path output by the high-speed light polarization conversion device and mainly used for adjusting the optical distance of selected pulses, and the arrival time of the basic pulse is matched by adjusting the optical distance of the delay light path, so that energy superposition of the two laser pulses is achieved. According to the structure, on the premise that the total laser power is not changed, introduction of an additional laser device is not needed, pulse energy can be doubled just by lowering the pulse repetition frequency and conducting pulse superposition, and therefore the utilization efficiency of laser power is improved.