Single crystals of AgGa(Se1-xSx)2 with x=0.20, 0.50, 0.75 have been prepared, and some optical properties are presented. Calculation made for the type I optical parametric oscillation by 1.06 μm radiation pumping shows that mid-infrared laser continuously tunable from 1.4 to 12 μm can be generated for the crystal AgGa(Se1-xSx)2 with x=0.65.