Concrete is a very complicated, random, multi-scale and multi-phase material. It is important to know cement paste structure to understand its properties and damage mechanisms that can influence the properties of concrete. Recently, many researchers have focused on the simulation of hydrated cement microstructure to figure out how damage/deterioration might be initiated. Moreover, as the microstructure of hydrated cement is known, we are able to produce greener, stronger and more durable concrete. There is a critical need to survey previous research to direct future study. In recent years due to development of advanced computers, most researchers tend to study the atomistic structure of hydrated cement and to make a bridge between nano and macro scales. Various models have been developed to simulate cement structure. This paper is an introductory review of the most important studies proposed by researchers for simulation of hydrated cement at different scales varying from nano to macro. Impact of the latest advances in simulation methods and their applications for hydrated cement research is investigated. Salient issues are categorised into four main sections including numerical models, microstructural models for cement hydration simulation, atomistic simulations and multi-scale studies.