Tungsten disulfide (WS2) is widely used in the fabrication of optoelectronic devices due to its remarkable saturable absorption characteristics. All-fiber passively Q-switched Er-doped fiber lasers based on WS2 saturable absorber (WS2 SA) are studied. With pulse laser deposition method, WS2 is uniformly grown on the tapered fiber surface. The gold film is deposited on the surface of WS2 to avoid WS2 being oxidized, and this method increases anti-interference capability of WS2 SA. With the balanced twin-detector method, the modulation depth of 15.2%, saturation intensity of 2.84 MW/cm2 and unsaturated loss of 78% of WS2 SA are measured. Stable Q-switched output pulse sequences of fiber laser with different pump powers are obtained when we rotate the polarization controller. When pump power ranges from 300 mW to 630 mW, the laser repetition rate can be tuned from 174 kHz to 250 kHz. Experimental results show that the narrowest pulse width is 780 ns, the maximum output power is 18 mW, the single pulse energy is 23.5 nJ, and the signal-to-noise ratio is 85 dB. The proposed Q-switched fiber lasers have good stability.