The principle and method for gas-solid interface study via low-energy pulsed electron beams are introduced, and the processes of adsorption-desorption and displacement are experimentally investigated. The desorption yields, threshold energies, and cross sections for N2 and O2 from polycrystalline Ni and W in vacuum (1×10-3Pa) at (T=300K) are measured. At the end of the paper, the conclusions are given.