The 2D Ising model is a simple yet powerful model to describe ferromag- netism. In this work, the phase transition and critical behavior of the 2D Ising model using the metropolis algorithm were investigated. Magnetization was an- alyzed as a function of temperature for lattice sizes L = 5, 10, 15, 20, 30. The analysis demonstrated a trend where the critical point becomes more sharply de- fined on increasing the lattice size. The value of the critical temperature obtained from the graph closely approximates the theoretical value. Hence, the simulation successfully demonstrated the phase transition of magnetic material from ordered to disordered state. The significance of Ising model further extends far beyond its application in understanding magnetism. This study provides a deeper under- standing of phase transition and critical behavior.