Abstract: One of the important performance indexes of the neutron monitor is the detection efficiency for different energy neutrons, which would directly affect the credibility and use of measured value. High sensitivity area neutron monitor produced by the Institute of High Energy Physics, Chinese Academy of Sciences was used to simulate its detection efficiency curve by Monte Carlo software, which shows detection efficiency firstly rises then decreases with the increase in energy, and the highest efficiency is at around 1 MeV. To verify the reliability and to compare trend changes of the detection efficiency curve, ray incident direction used in the simulation was changed. Based on this, 2.5 MeV single-energy neutron and 14 MeV single-energy neutron respectively generated by D-D neutron tube and D-T neutron tube were used to calibrate and verify the detection efficiency curve, and finally the detection efficiency curve of the neutron monitor was made.