Absorption spectrum of acetylene (C2H2) is used as the wavelength reference to calibrate the tunable fiber Fabry-Pérot (TFFP) filter in real time, and the accuracy of interrogation system based on TFFP has been improved. According to the free spectrum periodic characteristic of TFFP, a method to increase the wavelength calibration range was proposed. The system has a resolution of 1 pm over a working range of 1525～1615 nm in experiment. Compared with many traditional wavelength reference methods, this interrogation method is greatly improved in measurement precision, wavelength range and working reliability.