Method, system and device for service state transition of user equipment

The invention discloses a method, a system and a device for service state transition of user equipment. The method comprises the following steps: increasing the service state of UE which can be transited when the data size of a user plane is small and setting timing time for the service state which ought to be transited; when the set timing time is due and the data size of the user plane of the UE is smaller than a set threshold value, transiting the UE from the current CELL_DCH state to the increased service state; when the set time which is correspondingly transited to an IDLE service state is due and the data size of the user plane of the UE is smaller than a threshold value of the corresponding IDLE service state, transiting the service state of the UE to the IDLE service state. Therefore, the timing time for the service state which ought to be transited is dynamically set according to need and is commonly shorter than the timing time which is transited to the IDLE service state. The method, system and device disclosed by the invention can be used for guaranteeing balance between network resource occupying and UE experience.