The structural, electronic, mechanical and dynamical properties of XBC (X=Li, Na, Mg ve Ca) compounds with graphene-like planar boron carbide sheet are investigated by first-principles density functional theory calculations. A complete stability analysis is performed for the compounds: formation enthlpies are calculated to discuss energetic stability, elastic constants are calculated to discuss mechanical stability and phonon spectrum is calculated to discuss dynamical stability. Among the compounds, it is shown that all crystalline compounds except for the compound of X=Mg are energetically, mechanically and dynamically stable. Furthermore, in order to characterize mechanical properties of them, bulk modulus, shear modulus and Young modulus by means of calculated elastic constants, and alternatively bond strengths are calculated by combining crystal geometry and bond length information with atomic information. To clarify electronic behavior of the compounds, band structure calculations are preformed.