The invention discloses a machine tool vertical-axis rolling angle error measuring method based on double laser interferometers, and belongs to the technical field related to machine tool error measurements. The method comprises the following steps that (1) the two laser interferometers are provided, and arranged at two sides, opposite to each other, of a headstock of the machine tool; (2) positions and attitudes of the laser interferometers are adjusted to carry out focusing; (3) the machine tool and the laser interferometers are operated to measure and record data, and a mathematical model of the machine tool vertical-axis rolling angle error is established; and (4) measurement data is substituted into the mathematical model to solve rolling angle error values of different measuring points, a linear interpolation method is used to solve the rolling angle error of the headstock in the whole measuring course, and the vertical-axis rolling angle error of the machine tool is solved. Thus, all six vertical-axis error values are measured in one step while the rolling angle error is identified, the cost is reduced, the method is simple and efficient, and the measuring precision is higher.