The stylus retaining and releasing mechanism includes a housing, a push button and an eject piece. The housing includes a first sidewall, a second sidewall connecting with the first sidewall and a stylus assembling portion disposed on the second sidewall. The first sidewall defines an assembling hole therethrough configured for inserting or removing the stylus. The second sidewall defines a button hole therethrough. The stylus assembling portion defines an axial receiving hole therethrough communicating and being coaxial with the assembling hole to receive the stylus therein. The push button is elastically assembled to the button hole of the second sidewall to releasably lock the stylus. The eject piece fixed to the second sidewall and configured to provide a elastic pushing force to eject the stylus out as the push button is pressed.