Li metal batteries (LMBs) are one of the most promising high-energy-density batteries. However, solid electrolyte interphase (SEI) and Li dendrite substantially form in LMBs. Due to low ionic conductivity, inhomogeneity, and poor mechanical and electrochemical stability of native SEI, dendritic Li nucleates and grows, which in turn induces the fracture of SEI and promotes the formation of new SEI, causing the loss of active materials and safety issues for LMBs. Understanding the SEI–dendrite interactions could play a critical role in developing LMBs. For instance, modified SEI has been demonstrated to suppress dendrite growth and improve battery performance. In this short review, we discuss the underlying mechanisms of SEI–dendrite interactions and strategies for improving battery cycling performance.