The utility model relates to an adjustable slideway connecting support. Included are a main body and a movable member, wherein the main body comprises a first casing pipe connecting structure used forinstalling a casing pipe, the first casing pipe connecting structure is provided with a first side wall, the first side wall is provided with a hollow cavity, the movable piece comprises a second casing pipe connecting structure used for installing the casing pipe, the second casing pipe connecting structure is provided with a second side wall, and the second side wall is inserted into the hollowcavity and can slide. According to the adjustable slideway connecting bracket disclosed by the utility model, the length of the adjustable slideway connecting bracket can be adjusted by inserting themovable piece into the main body at different depths so as to adapt to slideway intervals in different projects, so that the adjustable slideway connecting bracket can be directly applied to 90% of projects only by developing a pair of dies.