Spasticity after stroke presents challenges to fundamental motor functions, crucial for independence and mobility. Despite persistent efforts, our understanding of its underlying mechanisms remains incomplete. Neuromusculoskeletal modeling shows promise for unraveling the pathological mechanisms of spasticity, but there is a variety of models, and synthesis would help to advance in this field. In this study, we carried out a systematic review to investigate the characteristics of models. PubMed, Compendex Engineering Village, IEEE Xplore, and Science Direct databases were used to perform a thorough literature search to identify relevant articles. Inclusion criteria were primary studies that explicitly modeled post-stroke spasticity in humans, without age or publication date restrictions, and studies published in English. We found eight relevant articles. To model the components of spasticity post-stroke, studies developed a theoretical framework that included musculoskeletal geometry, musculotendinous dynamics, muscle spindle modeling, motor neuron pool modeling, and subsequent muscle activations. Neuromusculoskeletal models primarily relate post-stroke spasticity to the hyperexcitability of the stretch reflex dependent on velocity. Non-neural mechanisms have also been considered to describe other contributions of joint hyper-resistance but to a lesser extent. On the other hand, the role of supraspinal centers has not been modeled, indicating a possible roadmap for future studies.