The birefringent interference filter for broad-bandwidth femtosecond pulse is investigated theoretically and experimentally. The principle and design of a novel birefringent filter are presented based on the interference of polarized light, the analytical formulation of transmission and reflection spectra out of the filter is obtained. The experiments of the filter for 15 fs broad-bandwidth pulse have been carried out, a group of good transmittance and reflection filter spectra is obtained in the experiments, the experimental measurements are in agreement with the theory. Moreover, the influence of the group velocity mismatch (GVM) and group velocity dispersion (GVD) on the filter for broad-bandwidth femtosecond pulse is analyzed. The results demonstrate that the filter is feasible and efficient for broad-bandwidth femtosecond pulse, and there is no power depletion since it allow output of the forward transmission and lateral reflection spectra synchronously. This kind of filter can be applied to developing stable multi-wavelength and tunable ultrashort pulse sources. The results can be importantly referenced by design and application of this kind of filter for femtosecond pulse.