The utility model discloses a concentricity adjusting device which comprises a supporting main body, a supporting bracket installed on the supporting main body and used for supporting semi-finished products to be expanded, a vertical adjustment structure installed on the supporting main body and used for adjusting the vertical position of the supporting bracket and a horizontal adjustment structure installed on the supporting main body and used for adjusting the horizontal position of the supporting bracket. The vertical adjustment structure and the horizontal adjustment structure capable of limiting and adjusting positions of the semi-finished products to be expanded in a mould are arranged between a semi-finished product heating device and an expanding mould. The concentricity adjusting device achieves adjustment and improvement of concentricity of products through adjustment and limiting of the positions of the semi-finished products to be expanded in the expanding mould.