Solving the magnetic target parameters (position, magnetic moment) using a three-axis magnetic sensor array is a typical nonlinear least squares optimization problem, and the Levenberg-Marquardt (LM) optimization algorithm is often used. However, when solving this problem, it is affected by observation errors such as sensor noise, which leads to less reliable results. In order to reduce the influence of observation errors, measurement noise and other effects on the solution results, in this paper, the principle of geometric accuracy factor is used to optimize the layout of the magnetic sensor array, in order to reduce the ability of noise and other observation errors to interfere with the magnetic parameter solving, and the accuracy of the magnetic target parameter solving is improved by decreasing the mean and variance of the geometric accuracy factor of the observation plane. After simulation experiments, we compare the mean and variance of the geometric accuracy factor of the observation plane with different arrangements of the three sensors, and find a reliable optimal layout scheme for the sensor array: the radius of the reference circle r is 20-30% of the observation plane; the sensor array is located in the arc of the reference circle and arranged in a positive triangle; and the distance between the plane in which the reference circle is located and the observation plane d is 0. It is verified that when the sensor arrays are not arranged in an optimized layout, the solution deviation [mx,my,mz] of the three-axis magnetic moment vectors using the LM algorithm is up to [0.0344,0.0279,0.0288]A?m2, and that of the positional solution deviation [x,y,z] is up to [3.37,3.14,3.31]cm; the optimized array layout reduces the maximum values of the solution deviation [mx,my,mz] and the maximum value of [x,y,z] are reduced by [75.37%,78.66%,76.74%] and [72.67%,92.83%,85.76%] respectively.The optimization of the sensor array layout is instructive for improving the accuracy of magnetic target parameter solving.