The invention relates to a thickness adjustable type accounting voucher wrap corner connected with a cover. The accounting voucher wrap corner comprises the cover connected with a wrap corner body; the wrap corner body comprises wrap corner pieces, connecting pieces and a center blocking piece, wherein the wrap corner pieces include a first wrap corner piece, a second wrap corner piece, a third wrap corner piece and a fourth wrap corner piece which are in rectangular shapes with same area, and the connecting pieces include a first connecting piece and a second connecting piece which are in triangular shapes with same area; a plurality of directional lines a, b, c, d and e and folding line indentations m, a1, b1, c1, d1 and e1 are formed on the inner surface of the wrap corner body. The accounting voucher wrap corner has the advantages that a user can freely cut out and manufacture wrap corners with different thicknesses according to the thicknesses of accounting vouchers, and the requirements of different conditions are satisfied; the wrap corner is connected with the cover so as to effectively prevent a bond accounting voucher from being swapped; the wrap corner is tight and attractive, and can prevent corners of the accounting voucher from being worn.