The invention discloses an assembled interval type ring main unit. The ring main unit comprises a ring main unit body, a detachable base cylinder is installed on the left side of the ring main unit body, racks are slidably arranged on the inner walls of the front side and the rear side of the base cylinder respectively, a gear rotationally arranged on the inner wall of the base cylinder is arranged between the two racks, and the two racks are matched with the gear respectively. Insertion plates are fixedly connected to one ends, away from the gears, of the racks, and detachable sleeves are installed at the positions, corresponding to the two insertion plates, of the right side of the ring main unit respectively. The ring main unit has the advantages that the two racks can be driven to move in the direction away from each other by rotating a rotary knob, and then the insertion plates can be driven to be inserted into the sleeves in a matched mode, so that splicing of two adjacent ring main units is achieved, operation is very convenient, the interval between the spliced ring main units is reduced, space waste is avoided, and the ring main units can be placed more stably; and when the two adjacent ring main units are disassembled, the knob is directly and reversely rotated.