For achieving engineering application of pentazolium anionic energetic materials， it is necessary to realize large-scale production of 3，5-dimethyl-4-hydroxyphenylpentazole （HPP） as the precursor of pentazole. The pilot synthesis techniques of HPP were performed based on accessibly lab-leveled method using 10 L and 100 L reactors for scale-up experiments. The dropping time of aqueous solutions of sodium nitrite and sodium azide， the purity and the feeding mass of 3，5-dimethyl-4-hydroxyaniline hydrochloride （DAC）， on the production of HPP were investigated. Results indicate that HPP production increases with the increasing of the total dropping time of sodium nitrite aqueous solution and sodium azide aqueous solution. After a certain value， the production of HPP remains. The purity of DAC affects the HPP production significantly that the production increases with the increasing of purity. With the scale up， HPP production increases along with the reducing of production ratio. With the feeding mass of DAC reached to 6 kg， a batch of product increased to 11.5 kg as well as the production rate decreased to 1.91.