According to the optical refraction characteristic of transparent solid,the key problem encountered in the measurement of solid refractive index by laser speckle method is analyzed and discussed,and three kinds of optical measurement systems including near-field speckle,far-field speckle and image plane speckle are buil for measurement.Firstly,two speckle patterns before and after solid refraction are recorded,and then the small in-plane displacement before and after refraction can be obtained.Finally,the refractive index of solid is calculated according to the theoretical formula.Using the existing and improved methods, a comparative experimental study on the refractive index of 3 mm thick solid glass has been carried out through traditional holography and digital holography respectively.