Embodiments of the present disclosure relate to a method, a device and a computer-readable medium for guaranteeing communication service. According to embodiments of the present disclosure, a source network device that currently serves the terminal device transmits, to a target network device which will serve the terminal device, information about the amount of resources of network slices utilized by the terminal device. The target network device configures the amount of resources based on the information. In this way, successful handover of the terminal device from the source network device to the target network device is guaranteed, so as to ensure continuity of communication services of the terminal device. In addition, embodiments of the present disclosure creates a network slice in the target network device, which avoids possible interruptions of communication service caused by mapping from the terminal device to the slices supported by the target network device.