Crossing is a fundamental paradigm for target selection in human-computer interaction systems. This paradigm was first introduced to virtual reality (VR) interactions by Tu et al., who investigated its performance in comparison to pointing, and concluded that crossing is generally no less effective than pointing and has unique advantages. However, owing to the characteristics of VR interactions, there are still many factors to consider when applying crossing to a VR environment. Thus, this review summarizes the main techniques for object selection in VR and crossing-related studies. Then, factors that may affect crossing interactions are analyzed from the perspectives of the input space and visual space. The aim of this study is to provide a reference for future studies on target selection based on the crossing paradigm in virtual reality.