A major challenge in hydrological modelling is to identification of optimal parameter set of different data, catchment characteristics and objectives. Although, the identification of optimal parameter set is difficult because of conceptual hydrological models contain more number of parameters and accuracy also depends upon all the relevant number of parameters influencing in a model. This identification process cannot estimate directly and therefore it measured based on calibrating the model which minimizing an objective function. Here, the objective function can depend upon the sensitivity of model parameters and calibration of model. In this paper, we proposed the Emulator Based Optimization (EBO) for reducing number of runs and improving conceptual model efficiency. Where, emulator models are used to represent the response surface of the simulation models and it can play a valuable role for optimization. In this study evaluates EBO for calibrating of SWAT hydrological model with following steps like input design, simulation model, emulator modelling, convergence criteria and validation. The results show that EBO calibrates the model with high accuracy and it captured the observed model with consuming less time. This study helps for decision making, planning and designing of water resources. © IAEME Publication.