Predators can not only control population size of prey through direct killing, but also influence reproductive outputs and population dynamics of prey through predation risk effects, which are the costs incurred by prey’s anti-predator behavioral change. Predation risk effects can have even stronger influences on prey population dynamics than direct killing of prey, but there have been relatively smaller number of field studies about the impacts of predation risk effects on population dynamics of preys during the past decades. This paper reviews the progress of researches about predation risk effects on population dynamics of preys with emphasis on introduction of several classical case studies involving Wolf (Canis lupus)-Elk (Cervus elephus) system in Yellowstone National Park of USA and Predator-snowshoe Hare (Lepus americanus) system in Yukon of Canada. This paper elaborates two hypotheses (predator-sensitive-food hypothesis and predation stress hypothesis) that have been proposed to illustrate the mechanisms underlying the impacts of predation risk on nutrition, reproduction and population dynamics of preys. There is evidence to support both hypotheses, but more researches are needed to further verify them. Considering that there have been few field studies about predation risk effects on prey population dynamics in China and the fact that many endangered species are facing increasing natural and anthropogenic stresses in China, I put forward recommendations and urge to conduct researches on predation risk effects (in addition to direct predation effects) on population dynamics of endangered ungulate preys in China.