The expressway occupies an important position in the highway network for its many feathers such as having large capacity, being fast and safe and so on, playing the role as the backbone of transport. With the rapid development of China's national economy and road transportation, the toll-by-weight expressway is being used in larger areas. To go further in research of the toll-by-weight model, it is essential to determine the charging standard by weight, so as to promote this toll-by-weight model as an important part of long-term mechanism curing overweight transport. This paper analyses several methods of the existing toll-by-weight expressway.