Due to the necessity and importance of the measurement of in-plane micro-rotations of a rigid body in the field of experimental mechanics, an investigation of quantitative measurement of rotation angle and rotation-center location is developed with digital image correlation method (DICM). The relation between the rotation angle and the in-plane displacement components is analyzed through theoretical analysis. The study of numerical simulation is carried out by specklegram produced by computer simulation. The measurement errors of both rotation angle and rotation-center location are within 2%. It shows that digital image correlation method is quite competent for the quantitative measurement of in-plane micro-rotations. The unknown in-plane rotation of a rigid body is practically measured by using digital image correlation method. The obtained rotation angle is compared with the result obtained from the geometrical optics experiment. The relative error is 3.1%. It shows that they are in good agreement. Experimental results indicate that digital image correlation method can be regarded as an efficient method to measure in-plane micro-rotations of a rigid body quantitatively.