The fatigue crack propagation rate at different points of aluminium alloy LD10cs butt-welded joints, tested by method of surface flaw has been discussed in this paper. The results show that the fatigue crack propagation rate at different points of the welded joints regularly varies with metal structure change resulting form the heatcycling of welding. The fatigue crack propagation rate of the fusion line and weld toe are greater than that of the others. The existence of the weld reinforcement will cause stress concentration at weld toe, and give worse infuence on the fatigue properties of this point, Hence, the fatigue properties of the weld toe will be the worst at welded joints. The various factors that affect the fatigue crack propagation rate at different points of the welded joints have been investigated and examined using optical metallography and scanning electronic microscope tochniques in detail. The suggestion to improve the quality of the welded joint has been presented.