The elasticity, vibration and thermodynamic properties of single crystal materials are very important in the field of laser and nonlinear optics. Therefore, it is very important to understand the physical mechanism of thermal properties in such systems. In this work, the structural, elastic, vibrational and thermodynamic properties of the AgGaxIn1-xS2 (x = 0, 0.25, 0.5, 0.75, 1) have been performed systematic within generalized gradient approximation (GGA) of Perdew-Burke-Ernzerhof (PBE). The results show that the AgGaxIn1-xS2 series have similar physical properties. When Ga concentration increases gradually, the lattice constants (a and c) decrease drastically with the increase of Ga content x. The polycrystalline elastic moduli including bulk modulus B, Young's modulus E, shear modulus G and Poisson's ratio v have also been successfully calculated. The brittle and ductile properties were judged by using B/G and Poisson's ratio. The anisotropy was characterized by calculating several different anisotropic indexes and the 3D figures of directional dependences of reciprocals of bulk modulus. Use the hybrid functional HSE06 to study the electronic properties of AgGaxIn1-xS2, and suggest that the HSE06 hybrid functional can obtain a more reasonable band. In addition, the optical spectrum are derived and main spectral features are interpreted in terms of the electronic structure. The calculated results of vibrational characters indicate that AgGaxIn1-xS2 (x = 0, 0.25, 0.5, 0.75, 1) are dynamic stability as increasing of Ga concentration from 0.0 to 1. Finally, the thermodynamic properties related to phonons have been realized and explored.