The invention discloses a method for measuring an in-plane polycrystalline texture. The method includes the steps: an X ray is emitted by an X-ray tube, wherein the X ray is a line focal spot; divergency of the X ray in a line focal spot length direction is limited by using a Sollar slit, and divergency of the X-ray in a direction perpendicular to the line focal spot length direction is controlled by using a divergence slit; the line focal spot X ray irradiates a to-be-tested product, and an X ray diffracted by the to-be-tested product is received by an X-ray detector; and the X-ray tube and the X-ray detector are controlled to perform Phi scanning on the to-be-tested sample, the intensity of the received X ray diffracted by the to-be-tested product is recorded by the X-ray detector, and the in-plane polycrystalline texture of the to-be-tested product is obtained according to the change of the intensity of the X ray diffracted by the to-be-tested product. Compared with the prior art, the measuring speed is greatly improved, the fluctuation range of the measuring value is greatly reduced, and the accuracy of measurement is maintained. Meanwhile, the method has the advantages of low cost.