Monte Carlo Simulation is a mathematical technique that generates random variables for modelling risk. This technique is suitable and benefits to the various client such as public and private sector to evaluate the realistic costing proposed by the Quantity Surveyor. Through this approach, quality of life received by the client in investing budget without waste of propose funding in the construction project. The methodology used is a qualitative approach consist of case study and document analysis. The result shows through Monte Carlo simulation, can predict the worst return from the accuracy of the estimation and given absolute confidence for project development.