A wavelength-switchable thulium-doped fiber laser (TDFL) based on a double fiber-tapered filter was proposed. Firstly, a Mach-Zehnder interferometer(MZI) filter was fabricated by cascading two fiber tapers produced by tapering single-mode fiber. Subsequently, a TDFL with a pump wavelength of 793 nm and a gain medium length of 3.5 m was designed and constructed, exhibiting a laser threshold of 126 mW. In the experiment, by adjusting the polarization controller (PC), a single-wavelength laser switching output within the range of 1 830.6—1 881.7 nm was achieved, with a minimum wavelength interval of 7.1 nm. Additionally, a dual-wavelength switchable laser output within the range of 1 841.7—1 881.1 nm was realized, with minimum and maximum wavelength intervals of 4.5 nm and 35.7 nm, respectively. During the 20 min monitoring period, the laser demonstrated stable single-and dual-wavelength outputs, with power fluctuations of less than 0.52 dB and 0.91 dB, respectively. The proposed TDFL exhibits flexible wavelength switching characteristics and holds significant application potential in laser sensing and measurement fields.