In order to improve the power factor of Magnetic-Geared Flat Linear Machine (MGFLM), this paper derives the analytical formulas of its air gap flux density and power factor, and investigates the influence of the variables on the basic physical quantities of the motor. The main variables affecting the power factor are determined as the permanent magnet distribution, the width of the tooth shoe and the shape and dimensions of the magnetizer block. Secondly, based on the parameterized finite element simulation of the MGFLM in Ansys Maxwell, a polynomial response surface model for the average thrust and power factor of the motor is established. Finally, Box-Behnken method was applied to optimize the motor. The power factor of the optimized MGFLM is increased by 44.9% from 0.497 to 0.720.