It is well know that the prisoner's dilemma game is a common phenomenon in ecology. Cooperator-defector interactions are ubiquitous in a population. One considered the ecological model was the cooperative evolution in the prisoner's dilemma game without the Allee effect. However, the Allee effect is a crucial phenomenon that has drawn considerable attention from ecologists. It describes a positive interaction among individuals in low population sizes, and these interactions may be critical for survival and reproduction. The Allee effect can be caused by any number of factors, for example, finding mates between the individuals of a species in low population densities, reduced defense against predators, special trends of social dysfunction, etc. Meanwhile, the Allee effect is a destabilizing factor in species persistence in the evolvement, and largely increases the possibility of the species' local extinction, even its global extinction. Many species, especially the endangered species, are more susceptible to the influlence of the Allee effect. Therefore, it is important to study cooperative evolution in a population with the Allee effect. Based on the system described by Feng Zhang & Cang Hui, we formulated a new prisoner's dilemma game model, in which the population was subjected to the Allee effect. Theoretical analysis and numerical simulation were used to investigate how the Allee effect influences cooperative evolution. The results show that, the assortment is still a necessary condition for the evolution of cooperation in the ecological context, and cooperative evolution becomes easier under density-dependent selection. At the same time, our study also indicates that the Allee effect can easily lead to the extinction of species, and acts against cooperative evolution under unfavorable environmental conditions. However, in the relatively superior environmental conditions (causing low death rate), the rise of cooperation could be much easier due to the Allee effect. As the Allee effect becomes stronger, it promotes more favorable cooperative evolution. However, the occupancy of a population will decrease as the strength of the Allee effect increases in the spatial pattern. When the value of the Allee effect is greater than the threshold value, the population eventually tends to become extinct.