A 2 μm distributed Bragg reflection (DBR) single-longitudinal-mode fiber laser with frequency tuning function is presented. The laser is based on single-mode thulium-doped silica glass fiber and pumped by 793 nm semiconductor laser pump source, and its optoelectric devices are integrated into a 1U chassis in a separate state. Fast frequency tuning of the laser can be realized through a built-in piezoelectric transducer (PZT), and the tuning range is about 6 GHz. The laser frequency can also be tuned without mode hopping in the range of 29 GHz through TEC temperature control. The output power of the single-longitudinal-mode laser is 18.2 mW, the signal-to-noise ratio is greater than 60 dB, and the pump conversion efficiency is 27%. This laser prototype is expected to play an important role in the fields of high-resolution spectroscopy, quantum information and nonlinear frequency transformation.