The invention provides a rapid damping method of a strap-down inertial navigation system, comprising the following steps: 1, carrying out preheating preparation n on the strap-down inertial navigation system; 2, carrying out initial alignment on the strap-down inertial navigation system; 3, conducting forward attitude matrix updating; 4, conducting forward speed updating; 5, conducting forward position updating; 6, storing the above data, and conducting initial reassignment of the attitude matrix, speed, and position, conducting reversible algorithm of the rap-down inertial navigation system; 7, conducting reverse attitude matrix updating; 8, conducting reverse speed updating; 9, conducting reverse position updating; and 10, conducting initial reassignment of the attitude matrix, speed, and position again, and repeating the step 3 to 9. According to the invention, the characteristics of mathematics platform variation of the strap-down inertial navigation system are fully utilized, a reversible algorithm is introduced, and the rapid convergence of system errors of the strap-down inertial navigation system is finally realized. The method disclosed herein can be used in the field of navigation error inhibition of marine strap-down inertial navigation systems.