This paper mainly studies the droplet breaking behavior in contracted pore throat microchannels. The droplet breaking process consists of four stages: extrusion, stretching, sub-droplet growth and fracture. The effects of interfacial tension and dispersed phase viscosity on droplet rupture were investigated. And changes in the localized pressure drop during droplet breaking. In order to understand the droplet deformation mechanism more deeply, we have successfully used micro-particle image velocimetry (micro-PIV) to describe the velocity distribution in the flow. The results show that the fluid characteristics of the continuous phase dominate the droplet deformation and fragmentation in the microdevice geometry. In addition, we built a model based on Taylor's analogy to predict the size of the child droplet formed when the parent droplet is broken during deformation, and compared it with the experimental data. The predicted model and the experimental data show a satisfactory agreement in terms of approximation.