Whole-bundle nerve recording is an easy technique to gauge central sympathetic outflow. However, this conventional technique often fails to detail individual fiber activities. Aiming for a signal resolution at the single-fiber level, we established a novel experimental model so-called as ‘oligofiber recording’. In vitro thoracic spinal cord-splanchnic sympathetic nerve preparations were obtained from Sprague-Dawley neonatal rats. Whole-bundle nerves were sucked into a glass micropipette containing 0.2% collagenase and incubated for 70–90 min. The dissociated nerve fascicles were then brought into another micropipette for electrical signal recording. Oligofiber activities that displayed several distinct spike potential (SP) waveforms were often achieved. Based on algorithms of κ-means clustering and principal component analysis, a series of custom-made MATLAB and LabVIEW programs were used for SP waveforms sorting. Using the oligofiber recording techniques, we could simultaneously examine several sympathetic nerve fiber activities and unravel their population firing behaviors at a resolution of single-fiber activity level.