Along with the rapid progress of the technologies in human computer interaction and affective computing

facial expression recognition has been actively researched. To clarify the research direction and development of facial expression recognition in human computer interaction

the research states of facial expression recognition are analyzed from the aspects of facial expression database

facial feature extraction

facial expression classification methods

robust facial expression recognition

fine-graded facial expression recognition

mixed facial expression recognition

and non-basic facial expression recognition. Finally

the study hotspots and trends of facial expression recognition are concluded

the limits in facial expression recognition are pointed out

and the expectation of the development of facial expression recognition is given.