The dimension of polyaniline (PANI) is effectively tuned by changing the end groups of additive surfactants. PANI fiberboards, dendrites, and rods are separately obtained through the guidance of micelle soft templates formed by the corresponding surfactants, i.e., sodium dodecyl sulfonate (SDS), sodium lauryl sulfonate (SLS), and sodium dodecyl benzene sulfonate (SDBS). Detailed mechanistic studies reveal that PANI structures are fabricated from a bottom-up self-assembly process where one-dimensional (1D) nanostructures are aggregated into higher order architectures. Electrochemical properties of these PANI nanostructures are examined in details, and exhibit morphological dependence. The PANI rods having high specific surface area and rough surface favor more ions enter into their body contact with active sites. As a consequence, they have higher specific capacitance (192 F g(-1)) than fiberboards (55 F g(-1)) and dendrites (64 F g(-1)) at 3.0 A g(-1). Varying the substituent of additive molecules is in a position to alter the dimension of PANI that plays a decisive role in resulting electrochemical performances. This strategy may control the dimension and the properties of other conducting polymers for future applications.