The invention provides a method for adjusting the height of a rolling line in the roll changing process on a rolling production line. The method comprises the following steps: (1) after roll changing, the parameters of a working roll after being replaced and a support roll are input to a control device; (2) the control device compares the parameters of the working roll after being replaced and the support roll with the maximum parameters of the working roll and the support roll provided in the control device, the adjustment quantity delta h of an adjusting device is determined, and the grade n of a trapezoidal backing plate is calculated; (3) the control device sends an instruction to the adjusting device based on the calculated grade n; (4) after receiving the instruction, the adjusting device automatically adjusts the trapezoidal backing plate to a corresponding grade n so as to adjust the height of the rolling line, thus causing the strip steel to horizontally pass through a roll gap as far as possible, which is beneficial to improving the rolling stability.