In this study, we report on the construction of multiple heterojunctions by functionalization of WO3-SnO2 n-n junction nanotubes (NTs) with nanoscale Pd catalysts for highly sensitive and selective acetone sensing. WO3-SnO2 n-n junction NTs with various W/Sn molar ratios were fabricated via an electrospinning technique. Pd decoration of WO3-SnO2 NTs was further developed by a chemical deposition method. As a result, the enhancement of sensing selectivity and sensitivity to acetone and reduction of operating temperature were simultaneously achieved. The enhanced sensing characteristics of Pd@WO3-SnO2 NTs were mainly ascribed to the formation of multiple heterojunctions (WO3-SnO2 n-n junctions, PdO-SnO2 and PdO-WO3 p-n junctions) and chemical sensitization effect of Pd nanocatalysts. The present results demonstrate that porous WO3-SnO2 heterojunction NTs decorated with nanoscale Pd catalysts have a good potential for sensitive and selective detection of acetone.