The breakup dynamics of the dispersed thread for droplet formation in shear-thinning fluids in a flow-focusing device was highlighted. The breakup process of the shear-thinning dispersed thread could be divided into four stages: the droplet growth stage and the squeezing stage, both of them are dominated by the squeezing pressure, the stretching stage controlled by the viscous stresses of dispersed phase and the surface tension, and the pinch-off stage controlled by the viscous stresses of both phases and the surface tension. The breakup dynamics of the dispersed thread for the shear-thinning fluids in each stage is very similar to that of the constant viscosity Newtonian liquids, signifying that the breakup is almost unaffected by the shear-thinning rheological properties. (C) 2017 Elsevier Ltd. All rights reserved.