Using a pair of Fiber Bragg grating Fabry-Pérots(FBG-FP)with a little different FSR as its wavelength-selective components,a novel ring laser based on the vernier effect is proposed.We have studied the characteristics of this kind of tunable fiber laser both theoretically and experimentally,and obtained 8 discretely tunable laser wavelengths ranging from 1552.240 nm to 1552.912 nm with an average 96 pm span by pulling the tunable FBG-FP.The output spectrum peak is uniform among different wavelength at -17.66 dBm with a fluctuation of 0.7 dB.When the pump power is 95 mW,the signal-to-noise ratio is better than 50 dB.The output spectrum of the laser is recorded automatically by an optical spectrum analyzer(OSA)once a minute.It is found that the output wavelength drift within a few pico-meter and the fluctuation of the output power is less than 0.1 dB.This kind of fiber ring laser may have potential applications in optical communications and sensors.