Variable cross section construction method for underground continuous wall

The invention discloses a variable cross section construction method for an underground continuous wall. The method comprises the following steps: surveying and setting out; constructing a guide wall; arranging a mud pit; processing lead holes in the groove segment of the underground continuous wall; taking soil with a grab machine to form a groove; cleaning the formed groove; preparing for hoisting a reinforcing cage; hoisting the reinforcing cage; and casting underwater concrete for the continuous wall, assembling a square caisson, hoisting and filling. The variable cross section construction method for the underground continuous wall has the advantages that the cost is low, the chisel workload of the follow-up construction is reduced, the construction period is short, the construction quality is stable, and the construction is convenient.