Abstract: An indirect spatial position algorithm is presented for separated water surface detector and its carrier (e.g. underwater vehicle) under the dynamic baseline. By translation and rotation transformation ofgeodetic coordinates at release position, underwater vehicle coordinates and separated water surface detector coordinates, as well as the double integral displacement vector operation based on linear accelerometer, the modeling of indirect spatial position algorithm for underwater vehicle and separated water surface detector under the dynamic baseline was established Simulation results show that the model reflects the spatial position of the underwater vehicle in the geodetic coordinates relative to separated water surface detector.