After carrying out simulation for Packed bed reactor, we decided to do the same for Continuous stirred tank reactors in series (CSTRs in series) which is also referred as Back mix or Mixed flow rectors are widely used in chemical process industries for conductions single as well as multiphase reactions. These reactions have provisions for continuous inflow of reactants and outflow of product mixture. A certain pool of reaction mixture is always maintained in the reactor so that there is no variation of concentration, temperature or reaction rate throughout the reactor volume. CSTR is having much attention because of its simulation is simple due to absence of temperature and concentration gradient within the reacting fluids. Mathematical modeling and experimental verification of the steady state and dynamic behavior of CSTRs in series is useful for designing of a safe operation of reactor with suitable control. Here, hydrolysis reaction of acetic anhydride in the presence of acetic acid as solvents and sulphuric acid as catalyst was chosen as a reactions system. Experiments were carried out for heat loss for all the three reactors as model and then simulation was carried.