In this letter, we investigate the effects of quintessence on thermodynamics of the Bardeen black hole and compare them with the results of our former paper. Black hole thermodynamic stability can be determined by studying the nature of heat capacity of the system. We use the first-law of thermodynamics to derive the thermodynamic quantities of these black holes and we compare and analyse the results. We plot the variation of mass, temperature and heat capacity as a functions of entropy related to the quintessence. Finally, we study the equation of state of these black holes with quintessence.