Abstract: The quality of cathode characteristics has a great impact on vacuum electronic devices and electron emission mechanism is very important in cathode characteristics. The problem of cathode electron emission has received sustained attention of researchers from various countries since the advent of Child-Langmuir's law early in the last century and the research on this issue focused on the improvement and development of model and numerical algorithm of cathode electron emission. This paper briefly reviews research results and progress in this field from the above two aspects and finally we put forward our own views.