Composites are commonly used in engineering applications. One example is the polymer-cement composites, where the polymers are used to modify/reinforce the cement mortar and concrete. In this regard, the bottom-up understanding of such complex nano-composites can be achieved through atomistic simulation and modeling at the atomic level. This review discusses the progress of molecular simulation in investigating polymer-cement interactions. Thus, the polymer-cement composites, including polymer-modified cement mortar and polymer-cement interface, as well as other interactions, such as chemical admixtures and corrosion inhibitors, are covered. In addition, the mechanisms involved in the polymer-cement interactions are reviewed. The research challenges in this area are discussed, and the need for future research and development prospects is also presented. To date, no survey on the simulation studies of polymer-cement interactions has been conducted. Thus, this review provides comprehensive molecular-level modeling in this area and, hopefully, it would motivate the researchers to conduct more studies.