The invention relates to a method for measuring the three-dimensional surface shape of an object by an electronic speckle phase shift technology, which comprises the following steps: (1) fixing an object to be measured on a reference plane which is connected with a phase shifter and can rotate in a vertical plane; (2) enabling the object to be measured and the reference plane to deflect slightly less than 5 degrees, and generating alternately dark and bright interference fringes on the surface of the object to be measured by interference of light; and (3) applying phase shift to the surface of the object to be measured by the phase shifter to change the optical path difference of the reference light and object light; carrying out equal four-step phase shifting on the curved interference fringes obtained in the step (2), wherein the alternately dark and bright interference fringes can make corresponding translation according to the size of the applied phase shift; obtaining a wrapped phase diagram by a four-step phase algorithm, and because the phases are wrapped between -pi and pi, serializing the phases by a phase unwrapping algorithm to obtain the true phase of the object to be measured; and deriving the height distribution of the object surface according to the mapping relation between the phase and the height, and obtaining the surface shape of the object. Meantime, the invention also discloses a system of the method.