This paper proposes an accurate method of main-transformer N-1 verification for distribution network, considering the capacity constraints of feeder and main-transformer, practical operating constraints and load transfer constraints. The verification model of transferring the load of N-1 main-transformer through closing normally open switches among feeders is established. This model also considers the situation that the load of N-1 main-transformer is transferred to the other main-transformer within the same substation through the bus connecting the two main-transformers. Combined with the practical work of distribution network planning, the proposed method is applicable to various wiring modes of distribution network and close to the actual network structure. The accuracy of the proposed method is verified in comparison with existing relative methods. This work is supported by National Natural Science Foundation of China (No. 51377058).