Abstract: In order to study the photoconduction terahertz radiative process of InSb semiconductors, carrier migration rate and surface current were simulated. Effect of femtosecond pulse lasers with different properties on the near field terahertz (THz) intensity was also analyzed. Surface current in the semiconductor material was analyzed with macroscopic electromagnetic theory and microscopic semiconductor theory respectively. Power spectrum curves of InSb and GaAs material were compared. The researches show that: the longer the InSb carrier auger relaxation time, the bigger the InSb carrier migration rate; the surface current is proportional to the carrier life and relaxation time; macroscopic electromagnetic theory is suitable for analyzing surface current; the bigger the saturated laser energy density, the stronger the near field THz intensity; the shorter the laser pulse width, the stronger the near field THz intensity; InSb material power is higher than GaAs material. The results lay a theoretical foundation for study on InSb photoconduction THz radiation.