With the development of IMT-2020 networks and beyond, it requires for more dynamical network capability to support diverse services, which increases the complexity of network slicing and puts forward higher requirement on the quality of service. Therefore, it is necessary to enhance network slicing mechanisms by digital twin for accurate implementing the requirement of real-time resource changes and evaluate network slice performance in advance. Digital twin for network slicing makes a potential solution for addressing higher efficient slicing resource utilization issues. This Recommendation specifies the overview, requirements, framework, network function enhancements, procedures and security considerations of digital twin for network slicing in IMT-2020 networks and beyond.