According to the structural feature of parallel single disk gate valve, the strength and rigidity of body will be calculated with finite element method, and with cylindroid shell theory.

This paper gives two kinds of calculation methods of natural frequency of a mass-even elliptic column which oscillates in miniamplitude on a plane, obtains two formulas of natural frequency.

The bending methods for elliptic and parabolic figure with variable-width mirror were discussed and the formula of variable-width for ladder-shaped mirrors was given.