A sea wave surge base alignment test device consisting of a linear motion guide rail, a stewart platform, a rotating mechanism, a cantilever beam and an electronic control system based on an EtherCAT fieldbus is designed. The linear motion guide and the stewart platform provide the seven movement dimensions for the whole device. the rotating mechanism, the cantilever beam and the linear motion guide widen the movement dimension and amplitude of the device.the EherCAT fieldbus effectively satisfies the real-time, synchronization and accuracy of the whole device. the whole system effectively satisfies the requirements of multi-degree, large amplitude, low frequency, large acceleration combined superimposed rocking motion and simulation motion in the sea wave surge simulation motion.