This paper proposes a new ranking method for the trapezoidal fuzzy numbers, which uses the possibilistic intervals of fuzzy numbers. These intervals are obtained by a partition from the support function of fuzzy numbers, and a new mean is defined based on them. This method is simple for ranking of the symmetric fuzzy numbers with the same modes and support functions, while the most ranking methods of fuzzy numbers cannot rank them, thus this method can overcome shortcoming of some of the previous ranking methods.