A structure fatigue life calculation method based on the non-linear cumulative damage theory comprises the following steps: firstly, performing a stress analysis on a metal structure through the finite element technology and determining a large-stress-value area as a dangerous area, secondly, determining initial damage of the structure according to a served age and surface quality detection of the structure, thirdly, measuring a stress spectrum of the structure in a certain period through a stress detector, fourthly, calculating cumulative damage of the structure under the stress spectrum through the non-linear cumulative damage theory, and fifthly, calculating a fatigue life of the metal structure through the cumulative damage. According to the method, the multi-stage load loading sequence and an influence of the size of a load on the cumulative damage are taken into account, and precision of the fatigue life is higher than the precision of a fatigue life calculated according to the linear cumulative damage theory. The method only needs a small amount of material performance data such as a cyclic stress-strain curve and a constant-amplitude strain life curve, calculation is simple, and the method is suitable for engineering applications.