The invention can apply to the communication technology and provide a switching method for communication conversation modes and the system and mobile terminal thereof. The method comprises the following steps: in a PTT conversation, test the web signal in PS region to find whether there is any err state, when any err state is detected, cut the communication interface of the PTT conversation module. Find the PPT service user who was cut by the communication interface and their identity identification information according to the mapping corresponding relations between the PPT service users andidentity indentification information thereof, connect the PPT service user to the common voice conversation mode interface and switch the PPT service to common voice conversation to avoid long time interruption due to errors of the web signal. The invention effective utilizes the communication capability of the current mobile terminals and is convenient for use.