A double-mode adjustable superresolving pupil filter based on birefringent filter is proposed. This filter can obtain superresolution in two modes of adjustment and is continuously adjustable. In the transversal rotation mode, the pupil filter acts as complex amplitude filter and as pure phase filter in the longitudinal tilting mode. By analyzing two superresolving parameters, the optimal designing parameters are got, which ensure a large field of view, a large superresolving range and a high setting accuracy. This filter can provide more flexibility in practical applications.