Microfluidic technology has advantages in producing high-quality droplets with monodispersity which is promising in chemical engineering, biological medicine and so on. An in-depth study on the underlying mechanism of droplet formation in microfluidics is of great significance, and to understand it, numerical simulation is highly beneficial. This article reviews the substantial numerical methods used to study the fluid dynamics in microfluidic droplet formation, mainly including the continuum methods and mesoscale methods. Moreover, the principles of various methods and their applications in droplets formation in microfluidics have been thoroughly discussed, establishing the guidelines to further promote the numerical research in microfluidic droplet formation. The potential directions of numerical modelling for droplet formation in microfluidics are also given.