In this paper, the Fourier transtorm method is used to solve the plane problems of an elastically anisotropical crystal thai has a two-hold symmetriceal axis. The stress distribution formulas of a crystal produced by the aetion of a point force are derived. Using these formulas the stress field of a, dislocation in the crystal is obtained. As an example, it is ealculated that the twined Zn crystal can lower its elastical energy about 35 per cent.