In order to obtain the widest wavelength tuning range, the cavity length of the tunable Fabry-Perot filter (TFPF) must be very small when used as a spectroscopic device in hyperspectral remote sensing. Differently from conventional Fabry–Perot interferometer, phase change occurring on reflection at each mirror can not be neglected when the cavity length is comparable with the resonant wavelength. In this paper, numerical calculations were carried out for the reflection phase shift on dielectric mirrors and filtering performance of TFPF in wide spectral range based on the Transfer-Matrix Method. Results show that TFPF exhibits higher spectral resolution and compressed wavelength tuning range after considering reflection phase shift. These research achievements can provide guidance for structure design and wavelength calibration of TFPF for hyperspectral remote sensing applications.