Determination of pollution source in sudden pollution accidents can be solved through convection-diffusion equation by reverse time integral. However, such method may result in divergence of numerical calculations. In this study, an objective function is established to solve the adjoint equation and the original equation by using the method of adjoint. Then, the extremums of the objective function are obtained by the successive iteration calculation method. In the end, the pollution source inversion can be realized. In order to verify the effectiveness of the method, pollution source was inverted by using the spatial and temporal distribution of the pollutant concentration, in which both single and double pollution source were included. The results show that the average relative errors between calculated values and analytical solutions are less than 15%, which can be accepted in engineering applications.