A method for sheeting deep trenches by means of supporting frames mountable lengthwise the trench at equal distances. The supporting frames comprise two parallel supporting elements and a rigid frame movable in the longitudinal direction of the supporting elements and connecting and keeping them spaced-apart, and large sheeting panels insertable into guide channels of the supporting elements. The supporting frames and the sheeting panels are pressed or lowered into the trench, following the direction of excavation. The rigid frame is movably guided between a lower stop and an upper stop along the supporting elements, whereby the lower stop is positioned at the required shovel clearance approximately 1 to 1.50 m from the end of the supporting element, and the upper stop is positioned at a distance from the lower stop, which distance corresponds to the height of the rigid frame, e.g., 1.75 m, and to an admissible support advance, e.g., 0.5 m. Once the supporting frame has been installed and lowered to a level at which the upper edge of the rigid frame is on the level of the trench's edge, the upper stops are removed, a second rigid frame is inserted into the supporting elements of the supporting frame, and the upper stops are fastened to the supporting elements at a distance above the second rigid frame. After lowering the supporting frame by another depth equal to a rigid frame, the upper stops are removed and, if necessary, a third rigid frame is inserted into the supporting elements of the supporting frame. The rigid frames are interconnected with each other to permit dismantling of the supporting frame.