Specimen preparation methods and the resulting fabric can significantly influence the mechanical behavior of sand. To clarify the influence of specimen preparation methods on liquefaction behavior, a series of undrained cyclic triaxial tests were conducted on sand specimens prepared by different methods with a wide range of relative densities. Then, mesoscopic tests, including scanning electronic microscopy and digital image processing methods, were systematically conducted to observe the initial fabrics produced by different preparation methods. The triaxial test results demonstrated that different specimen preparation methods produce distinctly different responses, including the stress–strain relationship, failure mode, liquefaction resistance, and critical state line. Analysis of the mesoscopic testing results indicated that the initial fabrics of the specimens were affected not only by the preparation methods but also by the relative densities. A reasonable explanation for the linkage between the macromechanical behavior of the sand and the fabric formed in the specimen preparation process is given in this study.