In this paper, the commercial FEM software package Abaqus is used to investigate the effects of microgrooved cutting tools in high speed orthogonal cutting of AISI 1045 steel. Microgrooves are designed and fabricated on the rake face of cemented carbide (WC/Co) cutting inserts. A coupled Eulerian-Lagrangian (CEL) finite element model is developed based on Abaqus to solve the evolution of the cutting temperature, chip morphology, cutting force, and phase constitutes simultaneously. This model is validated by comparing the numerical results with the experimental data for orthogonal high speed cutting of AISI 1045 steel with various cutting conditions. In addition, this model is also validated by comparing with the experimental data of regular tool and microgrooved cutting tool under the cutting speed of 120m/min. This validated CEL FEM model is then utilized to investigate the effects of microgrooved cutting tools on the phase transformation, cutting force, cutting temperature, and chip morphology in high speed orthogonal cutting of AISI 1045. The effects of microgroove width, edge distance (the distance from cutting edge to the first microgroove), and microgroove depth are examined and assessed in terms of cutting force, cutting temperature, chip morphology, and phase transformation. It is found that this CEL FEM model can capture the essential features of orthogonal high speed cutting of AISI 1045 using microgrooved cutting tools. It is also concluded that microgrooved cutting tools can not effectively reduce the cutting force in high speed machining, which is contrary to the conclusion obtained for low speed machining in previous research. However, microgrooves on the rake face have influence on the austenite percentage in the chip near the rake face. This research provides insightful guidance for optimizing the cutting performance in terms of cutting temperature, cutting force, chip morphology, and phase transformation in high speed machining of AISI 1045 steel.