Abstract: It analyzes and finds out that the geotextile soft mattress construction techniques, layout range and block-overlap of the Yellow River T-dam protective engineering have certain relations with the shape, depth and size of scour pit in front of the T-dam.The plane dimension of soft mattress depends on the ultimately stable depth and slope of scour pit in front of the T-dam.The depth of the scour pit and the length and width of soft mattress have been calculated, as well as the soft mattress layout form and blockoverlap techniques of the mattress body have been discussed.