Abstract: An HPGe detector was used to measure the hard X-ray energy spectrum produced by the interaction between the ultrashort pulse laser and copper solid target. The intensity of the P polarized light is about 8×10¹⁶W/cm². The experimental results show that the energy of X-ray is almost less than 100 keV and the temperatures of hot electrons are (7.4±0.7) keV and (19.5±1.4) keV, respectively under the condition that the angle of incidence of laser is about 45°and the detection solid angle is about 4.5×10^－6.