The invention discloses a rectangular Hall sensor array structure designing method for big direct current measurement. A round array structure is abandoned, and a Hall sensor array arranged in a rectangular mode is used; a high-order Simpson integration algorithm is adopted, the number of required Hall chips is decreased while the required measurement accuracy is reached, and the sensor manufacturing cost is reduced. By adopting the method, the accuracy and antijamming capability of Hall sensors are improved while the advantages of simple structure, low cost and the like of the Hall sensors are kept.