The phase transition and specific heat of carrier-induced diluted magnetic semiconductors (DMS) (Ga,Mn)As quantum well are investigated theoretically. With different concentration of magnetic ion and hole gas, there are three types of phase transitions, first-order, second-order and mixed first and second order. The specific heat of these three types of phase transitions are different, especially for the mixed-order phase transition, which shows two-step transition. The results indicate that the specific heat of DMS is a good tool to study the phase transition and critical phenomena of those quantum wells. (C) 2015 Elsevier B.V. All rights reserved.