Elastic properties are important in fundamental understanding of multiferroic materials. However, up to now, there is no work about anisotropy of elastic properties in orthorhombic Ca 3 Mn 2 O 7 . In this study, using coordinate transformation method, we investigated basic elastic parameters (elastic constants c i j ) and engineering elastic parameters (Young's modulus E , Poisson's ratio v , and the rigidity modulus G ) of orthorhombic Ca 3 Mn 2 O 7 along arbitrary orientations. The detailed anisotropic characteristics of these parameters were presented. The results reveal the orientation related elastic properties in mm2 point group orthorhombic Ca 3 Mn 2 O 7 .