We have calculated the bulk modulus and thermodynamic properties of Ni-2 XY (X = Mn, Fe, Co, Y = Ga, In) ferromagnetic shape memory alloys by first-principles density-functional calculations. It is demonstrated that in general, the bulk modulus and Debye temperature of each alloy decrease with temperature and increase with pressure, whereas the thermal expansion coefficient and the heat capacity of each alloy show an opposite trend. With the increasing atomic number of X or the decreasing atomic number of Y element, the bulk modulus and Debye temperature increase, whereas the heat capacity decreases but the thermal expansion coefficient does not make a big change.