The invention, which belongs to the technical field of the laser radar, provides a composite-modulation-pulse-code-based 4D imaging photon counting laser radar, so that a problem that the existing photon counting laser radar loses target strength information can be solved. The composite-modulation-pulse-code-based 4D imaging photon counting laser radar comprises a signal generator, a laser, a transmitting optical system, a unidirectional reflector, a scanner, a total reflection mirror, a receiving optical system, a narrow-band filter, a Gm-APD single photon detector, and a signal processing module. An optical signal outputted by the transmitting optical system is transmitted by the unidirectional reflector and is sent into the scanner; the scanner outputs an optical detection signal to a target; an echo signal reflected by the target is transmitted into the scanner; the echo signal outputted by the scanner is reflected by the unidirectional reflector and the total reflection mirror and the is transmitted to the transmitting optical system to carry out collection and echoing; the collected echo signal is filtered by the narrow-band filter and the is detected by the Gm-APD single photon detector; and a detection result is inputted into the signal processing module. The composite-modulation-pulse-code-based 4D imaging photon counting laser radar is mainly applied to target detection.