The invention, which belongs to the technical field of the rotation machinery fault diagnosis, especially relates to a divergence-index-based fault diagnosis method of a variable-working-condition wind-power planetary gearbox, wherein the method is especially suitable for the fault diagnosis field of the variable-working-condition wind-power planetary gearbox. The method comprises: on the basis of an order ratio re-sampling technology, pretreatment is carried out on a vibration signal collected by the variable-working-condition wind-power planetary gearbox sensor and a non-linear and non-stable time-domain signal is converted into an angular-domain signal with stability; because the planetary gearbox with the structural characteristics and diagnosis difficulties is different from the traditional fixed-shaft gearbox, faults of the planetary gearbox are graded and are diagnosed; a fault characteristic set is extracted; a fault diagnosis parameter is obtained; and then an experiment is carried out for verification. According to the invention, the non-stable characteristic of the vibration signal can be avoided and the fault characteristic order ratio can be identified effectively and clearly; the J-divergence and the KL-divergence can represent fault generation positions and types of the planetary gearbox; and when a fault occurs, a fault diagnosis can be carried out based on mutual assistance and the sensitivity is high.