The work aims to investigate the users' affective cognition mechanism on mobile news APPs from the perspective of user cognition. The event-related potentials (ERPs) technology was used to explore the users' affective processing process on homepage interfaces of mobile news APPs. In the experiment, the subjects were asked to evaluate the level of valence and arousal which were the two dimensions of affective experience for experimental stimuli, and the behavior and ERPs data were recorded at the same time. The behavioral results showed that the reaction time for arousal evaluation was shorter than that for valence evaluation, and the reaction time for low valence was shorter than that for high valence. The ERPs results showed that enhanced P2 was evoked by high arousal interface than low arousal interface, and greater N2 was found for low valence interface than high valence interface. Furthermore, enhanced LPP were evoked for low arousal interface in the right hemisphere of central region and for high valence interface in the left hemisphere of the central region. In the early stage of emotional stimulus processing, P2 and N2 can be used as significant indicators to measure the difference of users' affective experience; in the late stage of continuous processing and encoding of emotional stimuli, LPP can measure the difference of users' affective experience.