A methodology for setting up a realtime traffic control microsimulation and calibrating the microsimulation model at signalized intersection was proposed. The optimum values for calibration parameters were obtained by minimizing the error between the simulated and field platoon dispersion graphs. The methodology was applied to the intersection of Caoan Road and North Jiasong Road in Jiading District of Shanghai by using particle swarm optimization (PSO). Experimental results show that this methodology can work out a valid solution by only 11 iterations which can make its error less than 2%. The methodology proves to be effective and efficient and also provides a basis for testing or developing traffic control models at signalized intersection.