Dual-wavelength digital holography effectively expands the measurement range of digital holography, but it increases the complexity of optical system due to non-common-path of two wavelengths. Here, by using orthogonal polarization strategy, we present a dual-wavelength digital holography based on a Wollaston prism (DWDH-WP) to separate the reference beams of two wavelengths and realize the common-path of two wavelengths. A Wollaston prism is inset into the reference beam path of the off-axis digital holography system, so two orthogonal-polarized reference beams of two different wavelengths separated at different directions are generated. Then a dual-wavelength multiplexed interferogram with orthogonal interference fringes is captured by using a monochrome camera, in which both the polarization orientations and the interference fringe orientations of two wavelengths are orthogonal, so the spectral crosstalk of two wavelengths with arbitrary wavelength difference can be avoided. Compared with the existing DWDH method, the proposed DWDH-WP method can conveniently realize the common-path of the reference beams of two wavelengths, so it reveals obvious advantages in spectral separation, spectral crosstalk, system simplification, and adjustment flexibility. Both effectiveness and flexibility of the proposed DWDH-WP method are demonstrated by the phase measurement of the HeLa cell and vortex phase plate.