In this paper, we have studied the critical behavior and the magnetocaloric effect (MCE) simulation for the La_0.75Ca_0.1Na_0.15MnO₃ (LCNMO) compound at the second order ferromagnetic–paramagnetic phase transition. The optimized critical exponents, based on the Kouvel–Fisher method, were found to be: β = 0.48 and γ = 1. These obtained values supposed that the Mean Field Model (MFM) is the proper model to analyze adequately the MCE in the LCNMO sample. The isothermal magnetization M(H, T) and the magnetic entropy change −ΔS_M(H, T) curves were successfully simulated using three models, namely the Arrott–Noakes equation (ANE) of state, Landau theory, and MFM. The framework of the MFM allows us to estimate magnetic entropy variation in a wide temperature range within the thermodynamics of the model and without using the usual numerical integration of Maxwell relation.