This paper proposes a new method for optimizing the placement and size of distributed generation (DG) using type-2 fuzzy adaptive binary particle swarm optimization with single mutation operator, called T2FABPSOM. The objective function of the proposed method to minimize active power losses in transmission line with the bus voltage system constraints is allowed. Type-2 fuzzy logic system (type-2 FLS) is used for tuning the inertia weight w, the learning factors c 1 and c 2 parameters of particle swarm optimization to control the particle velocity. Single mutation also used in the proposed method as a combination to improve and strengthen the ability of particle to search for candidate solutions globally and avoid convergence to local optima. To evaluate the performance of the proposed method, the method is applied on IEEE 30 bus system. The proposed method compared with the binary PSO (BPSO) and fuzzy adaptive binary PSO (FABPSO). The simulation results indicated that the proposed method can determine the size and location of the optimal DG with a total active power losses are minimum compared to other methods.