Like other stegosaurians, "Huayangosaurus" was a quadrupedal herbivore with a small skull and a spiked tail. "Huayangosaurus" had the distinctive double row of plates of all stegosaurians. These plates rose vertically along its arched back. In "Huayangosaurus", the plates were more spike-like than in "Stegosaurus". Like "Stegosaurus" it had two pairs of long spikes extending horizontally near the end of its tail.