Cascading outages involve a series of dynamic phenomena that could lead to large blackouts and cause severe socio-economic loss. To better study these power system dynamic sequences when facing disturbance, a dynamic load model that mimics well the real behavior of the physical load is extremely important. Inappropriate load modeling could generate an inaccurate dynamic response in simulations and mislead system operation, which in turn may cause cascading outages. However, since load representation in a power system dynamic study is usually an aggregation of various types of load, it has the key nature of immense uncertainty. In the literature, several load models have been developed and verified for different scenarios. This paper discusses and compares a variety of state-of-the-art load modeling approaches for an application of cascading outage simulation.