In this paper, we have focused on a comparison of the different magnetic properties of the three nano-Heusler Ru$_2$Mn$_X$ (X = Nb, Ta or V) compounds using the Blume-Capel Ising model. The Heusler structures are composed by different mixed spins. In fact, the Ru and Mn atoms are modeled by spin-5/2 and spin-1/2, respectively. While, the X atoms ($X$ = Nb, Ta and V) are represented by the spin-7/2, spin-3/2 and spin-5/2, respectively. This study is carried out by using the Monte Carlo simulations under the Metropolis algorithm. The magnetic behaviors of the three nano-Heusler compounds have been studied and discussed. It is found that Ferrimagnetic to superparamagnetic transitions were observed corresponding to different blocking temperatures. Besides, the effect of the crystal field, the exchange coupling interactions and the external magnetic field have been inspected on the magnetization of each nano-Heusler compound Ru$_2$Mn$_X$ ($X$ = Nb, Ta or V).
