Plate falling film absorber with film-inverting configuration is a new kind of absorber that combines plate falling film absorption and film-inverting technique.By analyzing the fluid flow，heat and mass transfer processes in the absorber，a theoretical mathematical model was established.The control equation of the model was transformed by the flow function， discretized by the finite difference method， and used to numerically solve the case of lithium bromide solution falling film absorbed by using the TDMA algorithm.Comparison and analysis were made between the calculated result of the film-inverting plate falling film absorber and that of a same length vertical plate falling film absorber.It was shown that the newly developed absorber had better performance than the traditional plate falling film absorber under the same boundary and inlet conditions.