The method CND of non-destructive testing of a wind turbine blade includes: stressing the structure of the blade through a modification of a physical characteristic of a fluid filling the hollow interior volume of the blade; observing zones to be tested of the exterior surface of the blade, with the contactless measurement of a physical parameter on points of the exterior surface of the blade; and comparing the map of the values of the physical parameter measured with a reference map. A corresponding system CND for checking the structural integrity of a wind turbine blade includes an aerothermic device for modifying the physical conditions, temperature or pressure, of a fluid filling the hollow interior volume of the blade, a device for contactless measurement of a physical parameter, temperature or dimensions, of the exterior surface of the blade, and a device for processing the measurements.