The gradient magnetic field has been widely used in biomedicine and other fields. Electrical coils are often used in engineering to generate the required magnetic field. In practical application, the uniformity of the magnetic gradient coil has a great influence on the accuracy of measuring point positioning of the magnetic sensor. In this paper, the gradient uniformity is taken as the optimization goal, and the sequential quadratic programming (SQP) algorithm is creatively used to study the coil design and optimization method. Firstly, based on the design of the standard Helmholtz coil configuration, the parameters to be optimized are determined. The objective function of the magnetic field gradient uniformity is then established, and the objective function is iteratively optimized by the SQP optimization algorithm. Numerical simulation results show that the gradient uniformity of the magnetic field is greatly improved by optimizing the coil configuration.