Considering the plane elastic problem of one-dimensional hexagonal quasicrystals with point group 6mm, the theory about plane strain parallel to aperiodic direction is proposed and established. As an application of this theory, the analytic solutions of elastic fields of the quasicrystals with an elliptical cavity perpendicular to quasi-periodical direction are given in the form of general complex variable. In the limit case, our solutions degenerate into the ones of crack problems.