Designing of a sliding mode observer was finished based on the motion model of autonomous underwater vehicle (AUV). A Flutter decrease strategy for the sliding mode observer was discussed and the sliding mode observer was applied to the fault diagnosis of the AUV. Simulation experiment without faults was designed. https://www.roneverhart.com/Matchbook-Distilling-Ritual-Sister-Smoked-Pineapple-Eau-de-Vie-375ml-Half-Bottle/