The magnetic field and thrust of the double side aircored permanent magnet linear servo motor (PMLSM) were analyzed by analytical method and finite element method (FEM). The permanent magnets (PMs) were equivalent to the magnetization intensity distribution function based on the analytical method of equivalent magnetization intensity. The differential equations of the magnetic potential vectors were built up and solved by the separation variable method, and the analytical formulas of the magnetic flux density were derived. The magnetic field of the motor was also analyzed by FEM using the Ansoft Maxwell software, and the solutions of the FEM verified the correctness of the magnetic flux density formulas. Based on the 5poles,3coils short pitch winding structure, the dynamic thrust formula of the motor were derived. The relative error of the thrust computed by formula and FEM was 3.28%, which proved the accuracy of the analytical solution. The thrust formula shows that only sixoctave harmonic thrusts exist while the armature currents are perfect sinusoids, and the ripple thrust is very small. The analytical formulas are helpful for analyzing the magnetic field and thrust ripple which provide the basement for the motor optimization.