We used a Monte Carlo simulation to analize the magnetic behavior of Ising model of mixed spins S A = §3=2;§1=2 and ae B = §5=2;§3=2;§1=2, on a square lattice. Were studied the possible critical phenomena that may emerge in the region around the multiphase point (D=jJ1j = i3;J2=jJ1j = 1) and the dependence of the phase diagrams with the intensities of the anisotropy field of single ion (D=jJ1j) and the ferromagnetic coupling of exchange spin S A i (J2=jJ1j). The system displays first order phase transitions in a certain range of the parameters of the Hamiltonian, which depend on D=jJ1j and jJ2=jJ1j. In the plane (D=jJ1j;kBT=jJ1j), the decrease of jD=jJ1jj, implies that the critical temperature, Tc, increases and the first order transition temperature, Tt, decreases. In the plane (J2=jJ1j;kBT=jJ1j), Tc increases with the increasing of J2=jJ1j, while that Tt decreases.