The invention relates to a mother machine installation secondary grouting working method. The mother machine installation secondary grouting working method is performed according to the procedures: firstly, the preparation work for the secondary grouting, the base body of the mother machine is hanged up, the anchorage bolts are installed, the anchorage bolts, the adjustable iron pads and the backing plates are fixed on the base body of the mother machine through nuts, part of the adjustable iron pads and backing plates are positioned beside the foundation holes for supporting, and the foundation parts are hanged onto the supporting iron pads; secondly, the mother machine is roughly adjusted with a level meter; thirdly, the foundation secondary grouting is performed until the no hollow cavity or concave pit is found under the backing plate; fourthly, foundation maintenance is performed. Through the connection of the adjustable iron pads, the anchorage bolts and the backing plates with the foundation of the mother machine before the grouting in the invention, the secondary grouting is performed, to cause the foundation to be completely contacted with the adjustable iron pads, the foundation quality is guaranteed, the backing plates are grouted together with the foundation after the secondary grouting, and if the adjustable iron pad is damaged, the adjustable iron pad can be replaced arbitrarily, and the contacting effect of the adjustable iron pads with the foundation is not influenced.