In this work, the deformation of a droplet flowing through planar diverging and converging channels connected by a narrow straight microchannel is studied numerically. The solution of the depth-averaged Brinkman equation is obtained numerically via a self-consistent integral equation using the boundary element method. The droplet experiences a converging/diverging radial flow field as it flows in/out of the straight channel. Therefore, droplet deformation strongly depends on channel diverging angle. Our numerical results indicate that the maximum deformation of the droplet depends on the droplet size and the modified capillary number, and the channel diverging angle can be scaled with power laws with exponents 3.00, 0.70, and 0.50, respectively.