The invention provides a pulse infrared differential absorption laser radar system for detecting a carbon dioxide concentration profile, which comprises a laser emitting subsystem, an optical receiving subsystem and a data acquisition processing subsystem, wherein the laser emitting system comprises a seed laser, an Nd: YAG laser, a dye laser, a first reflecting mirror, a first half-reflecting half lens, a second half-reflecting half lens, a frequency doubling crystal, a difference frequency crystal, a first spectroscope and a wavelength control unit. The system can not only detect column concentration of atmospheric CO2, but also can obtain CO2 concentration profile distribution on a vertical path, particularly atmospheric CO2 concentration information near a boundary layer, and has important significance for carbon cycle research. The system has the advantages of low technical requirements, high stability, high detection precision and easy popularization, and is an important means for achieving atmospheric CO2 concentration profile measurement.