Mesh is an important component of electronic optical instruments such as streak cameras. In this paper, the finite difference method is used to model the wire diameter and wire hole of the mesh. The effects of the mesh on the disturbance of uniform electric field and the sub-lens effect of electron motion are analyzed. The secondary electron emission problem of collisions of electrons and mesh is studied by Gryzinski theory. The results show that the disturbances of the structural parameters are 0.31%, 0.07% and 0.04%, respectively, for the 10 line/mm, 33 line/mm and 50 line/mm mesh in the streak camera. For the electrons with energy of 15 keV, the non-elastic scattering collision free paths of Ni, Cr and Cu atoms are 6.85 nm, 10.34 nm and 7.25 nm, respectively, and it is difficult to produce secondary electron emission. The results have reference significance for the optimization of electronic optical instrument design and mesh parameters.