It has become a consensus to improve the measurement accuracy of microelectromechanical systems (MEMS) inertial measurement unit (IMU) through IMU array composed of multiple low-cost IMUs. In order to meet the accuracy requirements of the inertial navigation MEMS IMU array, it can be divided into two steps: the first step is to calibrate a single IMU in the array, and the second step is to isomorphically fuse the gyroscopes and accelerometers of multiple IMUs. This paper discusses an innovative calibration and fusion technology based on the accompanying test method and weighted fusion technology, which optimizes the two steps to improve the accuracy of the MEMS IMU array. The calibration is more efficient and does not require complex precision calibration equipment. We verified this method as a useful scheme by designing a principle prototype and experimental platform.