Ahstract-This paper focuses on the fluctuating target detec tion in low-grazing angle using Multiple-input Multiple-output (MIMO) radar systems with widely separated antennas, where the multipath effects are very abundant. The performance of detection can be improved via utilizing the multipath echoes. First, the reflection coefficient considering the curved earth effect is derived. Then, the general signal model for MIMO radar is introduced for fluctuating target in low-grazing angle. Using the Neyman-Pearson sense, detector of fluctuating target with multipath is analyzed. The simulation results show that the performance can be enhanced markedly when the multipath effects are considered.