Our daily life is filled with situations like tears of joy. For example, some fans scream frantically in rock concerts as if in horror in the presence of their teen idol, and some people playfully make ugly faces to an infantile baby and express their desire to pinch his or her cheeks. From the percepctive of emotion psychology, what these different situations have in common is that the internal positive experience not only indues positive expressions, but also negative expressions bound with negative emotion logically, which is defined as dimorphous expressions of positive emotion(DEPE; Aragón et al., 2015). This hypothesis has never been discussed and tested systematically before Aragón et al. (2015). The purpose of current paper is to introduce their pioneering researches and elaborate the sturcture and functions of DEPE, based on existing theories and studies of emotion and emotion regulation. First, there are two distinct expressions arising from a single stimulus, a single positive appraisal and a single emotional experience in this dimorphous-expression model that can explain the tears of joy well and is fundamentally different from any other theories, including the consensual process model of emotion generation, the mixed emotion model and the opponent-process theory of emotion. Aragón et al. (2015) proved the reasonability and generality of DEPE model, using questionnaire and experimental methods. Second, the occourence of dimorphous expressions of positive emotion means that individuals might feel overwhelmed with happiness. However, perhaps this intense positive emotion will result in many negative impacts to some extent: (1) In the physical, intense positive emotion may bring trouble to the mild and moderate asthma patients and influence some kinds of physiological indexes related to the clinical diseases; (2) In the psychological level, researcheres have revealed the effect of intense positive emotion on different mental processes, ranging from perception and attention to cogintive control and memory. Consequently, these negative impacts could prevent individuals from making reasonable judgements and then induce non-adaptive behaviors. Third, because of these passive influences induced by intense positive emotion, the regulatory function of DEPE will appear followingly. The mechanism contained in this process is that negative expressions of DEPE would help to down-regulate the uncontrolled positive emotion. Meanwile, the reasons for this approach may be: (1) In theory, researchers seemingly pay less attention to the theme of initiative suppressing positive emotions compared to negative ones; (2) Individuals rarely apply the cognitive reappraisal to positive events within a short time, because this dynamic process might occupy more cognitive resource; (3) Although quickly removing oneself from emotional situations is an effective way in the emotional responses stage, people will not always choose to do so. Obviously, exactly how these emotions are regulated through the expression of a second expression will need to be explored in future research. Finally, this paper discusses the future directions of DEPE. Psychologists should employ new paradigms and techniques of the cognitive neuroscience(e.g., event-related potential, functional magnetic resonance imaging) to investigate the neurophysiological mechanism of DEPE. By doing so, it’s benefical to reveal its unconscious process characteristic and the modality effect of this unique phenomenon as well. What’s more, the limitation in exiting studies help us to recognize the diversity of influencing factors on DEPE, which may be a valuable research field. It should also be noted that the future work could extend to explore its inter-personal function, not just be confined to the intra-personal level.