For group decision making problems in which the criteria values are interval-valued intuitionistic trapezoidal fuzzy numbers, some new additive operational laws of the interval-valued intuitionistic trapezoidal fuzzy number are defined, and based on these operational laws, some interval-valued intuitionistic trapezoidal fuzzy number arithmetic aggregation operators are proposed, such as the interval-valued intuitionistic trapezoidal fuzzy number weighted arithmetic averaging (IVITFNWAA) operator, the interval-valued intuitionistic trapezoidal fuzzy number ordered weighted averaging (IVITFNOWA) operator and the interval-valued intuitionistic trapezoidal fuzzy number hybrid aggregation (IVITFNHA) operator. Furthermore, on the basis of the IVITFNWAA operator and the IVITFNHA operator, an approach is developed for solving group decision making problems, in which the criteria values are interval-valued intuitionistic trapezoidal fuzzy numbers and the criteria weight information is known completely. Finally, an example is given to illustrate the feasibility and effectiveness of this method.