In this paper, a time of flight neutron reflectometer model is proposed. According to the original objective inputting physical parameters and expectations, computer simulation was done by McStas package. With the open slit, neutron flux at sample position was about 1×10⁵ n·cm^–2·s^–1, and the optimal resolution could reach 0.5%. The results show that the model has a good performance. The design of this model can be an instruction for neutron reflectometer construction or project analysis in the future.