In this study, structural, electronic, elastic and dynamic properties for LiInSi in the half-Heusler structure were analysed with the generalized gradient approximation using the density functional theory. The results obtained are compatible with the structural and electronic properties in literature. In addition to the results related to electronic properties in literature, cohesive energy and formation energy values were calculated. These values were found to be 10.333 and -0.884 eV, respectively. Elastic constants, bulk, shear, Young's moduli, Poisson's coefficient and Zener anisotropy factor values of LiInSi alloy were revealed. In addition, using linear phonon theory, phonon dispersion curve and phonon density of states graph were obtained. It has been calculated that while the LiInSi alloy is dynamically stable in the ground state, it becomes unstable under nearly 615 kbar pressure. Elastic and dynamic properties are presented in literature for the first time. It is expected that these results will be a guide for future studies.