Kinetochore is a protein scaffold coordinating the process of chromosome segregation in mitosis. The conserved Ndc80 complex is located on outer kinetochore to connect kinetochore with microtubules,and to stabilize the microtubule-kinetochore attachment. Aurora B /Ipl1 kinase parties involved in correcting the attachment errors. Ndc80 complex is also essential for the functions of spindle assembly checkpoint. This article reviews the current progress in Ndc80 complex studies.