Nickel-based superalloy is a critical material for turbine engine components in the aerospace application, but the poor machinability and low machining efficiency have further hampered it to be used widely. Cubic boron nitride (cBN), having extreme hardness and chemical inertness, is the potential candidate to process superalloys. In this paper, we systematically investigated the tool wear characteristic of cBN at different cutting speeds in dry turning of Inconel 718 by experiments and FEM simulations. The FEM model with initial flank wear land (VB) was established and validated. Effects of cutting speeds (200–400 m/min) on cBN tool life and wear mechanisms were systematically investigated. Effects of tool flank wear on cBN tool cutting edge temperature field and Inconel 718 machined surface layer stress distribution were analyzed by FEM simulations.