The electrophysiology technique now provides an alternative way to evaluate users’ emotional states in real time, but how to confirm the valence of emotions using these techniques is still a concern to researchers. Frontal alpha asymmetry (FAA) is often used as an index of pleasantness or liking in neuromarketing, but results in related fields are not consistent. In this study, we investigated the emotional states of users interacting with mobile phone applications (APPs) using FAA. Twenty participants participated in this experiment. They were asked to complete several tasks in a scene of everyday life using three APPs of the same type. EEG data and subjective evaluations were recorded during the experiment. The FAA results showed a positive trend when using an APP that provided an excellent user experience. The mechanism of emotional change during interacting with mobile applications and the implications of this research are also discussed in this study.