The invention discloses a multifunctional communication interface adapter, and relates to the technical field of communication. The adapter solves the problem that existing intelligent electric energymeter testing devices have no uniform communication interfaces. The adapter includes a microprocessor module, an RS485 module, an RS232 module, a CAN module, a first Ethernet module, a second Ethernet module and a power supply module. The communication interfaces of various intelligent electric energy meter testing devices can be unified to Ethernet interfaces by the adapter, and therefore, the interconnection capability between testing devices can be enhanced, the labor intensity of testing personnel can be reduced, and working efficiency and degree of automation can be enhanced.