The invention discloses a modular smart socket, and belongs to the field of electrical appliances. The socket comprises a power output end connected with a mains supply, the power output end comprises a metal insert, the socket further comprises a first circuit board and a second circuit board, the first circuit board is connected with the mains supply, and the first circuit board is connected with the second circuit board by plugging; a part of the metal insert penetrates through the second circuit board and is in electrical contact with the first circuit board; and the first circuit board and/or the second circuit board are provided with an expansion interface reserved for an expansion module. In addition, the invention further discloses an assembly method of the smart socket. The smart socket has the advantages that the structure is compact, the subsequent functional expansion is also facilitated, and the assembly is also more convenient.