The utility model discloses an underground diaphragm wall structure. The continuous wall comprises a continuous wall body and a reinforcement cage arranged in the continuous wall body, the reinforcement cage comprises a plurality of reinforcement cage bodies arranged in sequence, I-shaped steel is arranged on the two sides of each reinforcement cage body, and the I-shaped steel of every two adjacent reinforcement cage bodies is fixedly connected to enable the multiple reinforcement cage bodies to be connected into a whole. According to the underground diaphragm wall structure, the I-shaped steel is arranged on the two sides of the steel reinforcement cage bodies, the I-shaped steel of every two adjacent steel reinforcement cage bodies is connected to enable the multiple steel reinforcementcage bodies to be connected into a whole, alignment of the steel reinforcement cages is guaranteed, and therefore alignment of adjacent wall sections is guaranteed. The device is simple in structure,good in using effect and easy to popularize and use.