In the high-speed optical communication network, the present optical network switching capability and transmission capability are seriously unbalanced. Therefore, building all-optical network (AON) is an effective way to solve the problem. However, all-optical packet switching technology has not been achieved due to immature all-optical logic devices. The all-optical 2-to-1 data selector is proposed based on sum-frequency generation SFG+DFG and difference-frequency generation (SFG+DFG) in quasi-phase-matched cascaded periodically poled lithium niobate (PPLN) waveguides. The waveforms and the eye diagrams are obtained by numerical calculation and simulation, and the performance of the data selector is analyzed by the parameters such as pulse width, extinction ratio and peak power delay time. The results show that the signal light is processed using the PPLN waveguide cascade method. It can not only complete the corresponding logic function, but also can guarantee the transmission quality of the signal, which expands the capability of PPLN waveguide on the all-optical logic signal processing.