Seventy eight patients who need bedside temporary cardiac pacing through left subclavian vein were divided into 2 groups. In group A (n=40) the "three-point measurement" method was applied: a was set for puncture point of left subclavian vein, b was the middle point of angulus sterni, c was the right edge of the sternum at the 4th intercostal space, the length of ab + bc was used to estimate the depth of right atrium for electrode to reach until the success of right ventricular pacing. In group B (n=38) the puncture to the right or the left subclavian vein for temporary pacing was performed with X-ray guidance in catheter lab. Total rescuing time, procedure time and the threshold voltage of cardiac pacing was recorded in each groups. All cases were successful paced without complication related emergency cardiac pacing with a successful rate of 100% in both groups. There was not difference between two groups in the procedure time and the threshold voltage of cardiac pacing (P > 0. 05). The total rescuing time of A group was (10.0± 2.2) min, and that of B group was (30.5±3.5) min (P<0.01). The average depth of the electrode was ab + bc +9.0 cm. The results suggest that "three-point measurement" method is valuable in the guiding of bedside emergent cardiac pacing through the left subclavian vein.