A USB (Universal Series Bus) interface, comprising a USB interface main body, an inserting tongue of a power line configured for coupling to an external power line via inserting portions (31; 33), an inserting tongue of a ground line configured for coupling to an external ground line via inserting portions (71; 73), a power pin (8; 9) configured for charging a cell in a mobile terminal through a terminal and a ground pin (13; 14) configured for forming a charging circuit for charging the cell, wherein a bottom of the inserting tongue of the power line and a bottom edge of the inserting tongue of the ground line are coupled to the USB interface main body; the inserting tongue of the power line has P inserting portions (31; 33) extending therefrom, where P is greater than or equal to 2; and the inserting tongue of the ground line has Q inserting portions (71; 73) extending therefrom, where Q is greater than or equal to 2; there are M power pins (8; 9), where M is greater than or equal to 2, and each power pin (8; 9) is coupled to the bottom of the inserting tongue of the power line, wherein M power pins (8; 9) are coupled to a bottom of the inserting tongue of the power line; there are N ground pins (13; 14), where N is greater than or equal to 2, and each ground pin (13; 14) is coupled to the bottom of the inserting tongue of the ground line, wherein N ground pins (13; 14) are coupled to a bottom of the inserting tongue of the ground line; wherein, at least two charging circuits are formed by the P inserting portions of the inserting tongue of the power line and the Q inserting portions of the inserting tongue of the ground line when the USB interface is connected with a USB plug; wherein at least one inserting portion in the inserting tongue of the power line has a length shorter than that of other inserting portions in the inserting tongue of the power line; and at least one inserting portion in the inserting tongue of the ground line has a length shorter than that of other inserting portions in the inserting tongue of the ground line. the inserting tongue of the power line has P inserting portions (31; 33) extending therefrom, where P is greater than or equal to 2; and the inserting tongue of the ground line has Q inserting portions (71; 73) extending therefrom, where Q is greater than or equal to 2; there are M power pins (8; 9), where M is greater than or equal to 2, and each power pin (8; 9) is coupled to the bottom of the inserting tongue of the power line, wherein M power pins (8; 9) are coupled to a bottom of the inserting tongue of the power line; there are N ground pins (13; 14), where N is greater than or equal to 2, and each ground pin (13; 14) is coupled to the bottom of the inserting tongue of the ground line, wherein N ground pins (13; 14) are coupled to a bottom of the inserting tongue of the ground line; wherein, at least two charging circuits are formed by the P inserting portions of the inserting tongue of the power line and the Q inserting portions of the inserting tongue of the ground line when the USB interface is connected with a USB plug; wherein at least one inserting portion in the inserting tongue of the power line has a length shorter than that of other inserting portions in the inserting tongue of the power line; and at least one inserting portion in the inserting tongue of the ground line has a length shorter than that of other inserting portions in the inserting tongue of the ground line.