A　dual-wavelength　passively　Q-switched　Yb:　GdYSiO5　laser　based　on　a　WS2　saturable　absorber　mirror　was　proposed.　The　WS2　nanoplatelets　solution　was　coated　on　a　BK7　glass　substrate　with　high-reflective-index　thin　polymer　to　be　a　WS2　saturable　absorber　mirror　for　starting　Q-switching　operation.　By　tuning　the　resonant　cavity　and　selecting　a　suitable　pumping　power,　the　stable　Q-switched　laser　pulses　at　1051　nm　and　1091　nm　were　simultaneously　generated　with　a　976-nm　fiber-coupled　diode　laser　as　pump　source.　The　laser　pulses　had　a　pulse　duration　of　8.4　μs,　a　repetition　rate　of　2.9　kHz,　and　an　average　output　power　of　125　mW,　respectively.　©　2018,　Science　Press.　All　right　reserved.