The invention provides a control device of a conductor holder in a 
sewing machine, belongs to the mechanical technology field, and solves the problems of the prior conductor holder, such as low accuracy, etc. caused by manually regulating a line tension 
pulley of the conductor holder for controlling the line tension. The control device of the conductor holder in the 
sewing machine is characterized in that the conductor holder is arranged on the frame side part of the 
sewing machine; the control device comprises an 
electric motor, an 
electromagnet, a wire loosing rod and a wire clamping block; the 
electric motor is permanently connected with the frame; a wire clamping transmission mechanism which enables the wire clamping block to compress a spring is arranged between the 
electric motor and the wire clamping block; the 
electromagnet is permanently connected with the frame; and a wire loosing transmission mechanism which enables the wire loosing rod to prop against the outer end of a thimble is arranged between the 
electromagnet and the wire loosing rod. The control device realizes line tightening by the electric motor and the line clamping transmission mechanism, and the clamping force between an upper chuck and a lower chuck is always maintained to be proper during the process of line tightening. The control device of the conductor holder in the sewing 
machine has higher working stability and simple structure.