Abstract: The basics and the d2q9 (two-dimensional nine-point) model of the lattice Boltzmann method are introduced, and the advantage of its direct pressure calculation is demonstrated.A more efficient model for simulating pressure fields, namely d2q9p, an improved version of d2q9, is presented.Using the model, 2-D steady and unsteady viscous flows past a circular cylinder are simulated.Good agreement between results of the LB and those of other methods shows that LB method is a simple, efficient and accurate approach to simulate pressure fields.