The invention discloses a modular exploding welding explosive charging unit. The modular exploding welding explosive charging unit comprises cuboid grid type explosive charging units consisting of wall surfaces and bottom surfaces, wherein inner cavities of the grid type explosive charging units are divided into a plurality of explosive charging cavities in rows, and all grids of the inner cavities of the grid type explosive charging units are separated into structures communicating with each other by the hollowed wall surfaces. The invention further discloses a modular explosive charging splice-paving method of the modular exploding welding explosive charging unit. Structural materials of which the physical and chemical properties are matched with the exploding wave spreading properties of explosive are selected, a series of explosive charging units of which the length, width and height geometric sizes are modular are made, and an adhesive and the powdery explosive are mixed and poured in the explosive charging cavities so as to realize explosive charging solidification and form modular explosive charging. The exploding welding explosive is poured in the explosive charging units,so that the current field site explosive charging operation is changed into production line explosive charging, the manual explosive charging operation procedure is reduced, and the safety of exploding welding operation is improved.