The invention discloses a ship and boat shafting service life predicating method on the basis of vibration fatigue coupling analysis. The method comprises the steps of selecting a measuring time point ti, measuring the inherent frequency omega i (for n times of measurements, i=1, 2, 3, ..., and n and i are positive integers) of a ship and boat shafting located in the measuring time point ti, then, calculating the expected fatigue service life Ni when the ship and boat shafting is located in the measuring time ti, and finally calculating the remaining service life Mi when the ship and boat shafting is located in the measuring time ti. The method overcomes the defects of an existing method, starts from a ship and boat shafting model, calculates the service life of the ship and boat shafting on the basis of vibration and fatigue coupling environments, solves the problem that calculation and predication of the ship and boat shafting service life are not involved in the prior art, is easy to understand and easy to realize, and is more suitable for calculation and prediction of the remaining service life of the ship and boat shafting.