The invention relates to an adjustable connecting assembly. The adjustable connecting assembly comprises a first connecting piece and a second connecting piece which are connected with each other and further comprises a rotating shaft, a sleeve and a clamping sheet; the sleeve is arranged on the second connecting piece, connected with the first connecting piece and provided with an insertion hole, the rotating shaft is arranged in the insertion hole and can rotate, the clamping sheet is connected with the rotating shaft, the first connecting piece is provided with multiple clamping grooves, and the clamping sheet can be inserted into the clamping grooves. The adjustable connecting assembly improves the installation efficiency of decorative materials, is convenient to disassemble and low in labor cost, does not need to be operated by professional staff, achieves popularized construction, increases the construction speed and is beneficial for standardized operation.