A coil for a transducer includes a pair of first sections, a second section connecting to two ends of the first sections, and a third section connecting the other two ends of the first sections for forming a closed loop. The third section includes a pair of first stretch parts each extending from one first section toward the other stretch part, and a first extruding part extending from the first stretch parts away from the second section. The present coil can optimize the performance of the speaker.