The linearity tunable fiber ring laser based on closed-loop piezoelectric ceramics (PZT) is proposed. The fiber Bragg grating (FBG) of the ring cavity is fixed on the PZT, the wavelength of FBG changes with controlling the PZT, which leads to the wavelength change of fiber ring laser, so the tunable fiber ring laser based on PZT is realized. The strain sensor attached on the PZT is monitoring the step change of the PZT real-timely, reporting to the PZT driver system, compensating and rectifying the inherent hysteresis and creep through the Wheatstone bridge, so the tunable fiber ring laser based on closed-loop PZT is achieved. Experimental results show that the tuning curve of the fiber ring laser is linear with the tuning range nearly of 0.9 nm and the linewidth nearly of 4 KHz. Furthermore, the wavelength fluctuations of the tunable fiber ring laser are kept within ±0.01 nm, and the power variation is kept within ±0.3 dB.