A D-side sleeve lead connecting fitting comprises two wire clamp bodies, wherein one sides of the two wire clamp bodies are formed into transformer sleeve lead-out holes, and the other sides of the two wire clamp bodies are provided side by side with two groups of glands; four lead lead-out holes in the same direction are formed between the glands and the wire clamp bodies; each group of glands are composed of two outer glands and an inner gland; the wire clamp bodies are provided with screw holes, and the outer glands are fixed to the wire clamp bodies through bolts in the screw holes; the transformer sleeve lead-out holes are perpendicular to the lead lead-out holes; positions on the wire clamp bodies, which are corresponding to the transformer sleeve lead-out holes, are provided with copper aluminum composite sheets; and for a part of each lead lead-out hole being corresponding to the wire clamp bodies and the outer glands, the diameter of the outer side segment of the part is larger than that of the inner side segment of the part, and an alleviation transition groove is arranged between the inner side segment and the outer side segment. The D-side sleeve lead connecting fitting is suitable for indoor direct-current substations, has large current-carrying capacity, does not generate corona, can reduce conductor resistance, and can guarantee that the leads are tightly pressed and that the leads are not damaged at wire clamp outlets during long-term operation of the project.