Humanized mice, defined as mice with human immune systems, have become an emerging model to study human hematopoiesis, infectious disease, and cancer. Here, we describe the techniques to generate humanized NSGF6 mice using adult human CD34 + hematopoietic stem and progenitor cells (HSPCs). We describe steps for constructing and monitoring the engraftment of humanized mice. We then detail procedures for tissue processing and immunophenotyping by flow cytometry to evaluate the multilineage hematopoietic differentiation. For complete details on the use and execution of this protocol, please refer to Yu et al. 1 .