There are two kinds of dispatching policies in content-aware web server cluster: segregation dispatching policy and mixture dispatching policy. Traditional scheduling algorithms all adopt mixture dispatching policy. They do not consider that dynamic requests serving has the tendency to slow down static requests serving, and that different requests have different resource demands, so they can not use clusters resource reasonably and effectively. This paper uses stochastic reward net (SRN) to model and analyze the two dispatching policies, and uses stochastic Petri net package (SPNP) to simulate the models. The simulation results and practical tests both show that segregation dispatching policy is better than mixture dispatching policy. The principle of segregation dispatching policy can guide us to design efficient scheduling algorithm.