Current constitutive theories face challenges when predicting the extremely large deformation and fracture of hydrogels,which calls for the demands to reveal the fundamental mechanism of the various mechanical behaviors of hydrogels from bottom up.Proper hydrogel network model provides a better approach to bridge the gap between the micro-structure and the macroscopic mechanical responses.This work summarizes the theoretical and numerical researches on the hydrogel network models,aiming to provide new insights into the effect of microstructure on the swelling-deswelling process,hyperelasticity,viscoelasticity and fracture of hydrogels.Hydrogel network models are divided into full-atom network models,realistic net-work models and abstract network models.Full-atom network models have detailed atomic structure but small size.Realistic network models with different coarse-graining degree have large model size to explain the swelling-deswelling process,hyperelasticity and viscoelasticity.Abstract network models abstract polymer chains into analytical interactions,leading to the great leap of model size.It shows advantages to reproduce the crack initiation and propagation in hydrogels by simulating chain scission.Further research directions on the network modeling are suggested.We hope this work can help integrate the merits of network modeling methods and continuum mechanics to capture the various mechanical behaviors of hydrogels.