To study the variation trend of hydroxy-α-sanshool from Zanthoxylum bungeanum exposed to UV radiation and its transformation direction, the hydroxy-α-sanshool, a typical alkylamides of Zanthoxylum bungeanum, was extracted, separated and purified from Zanthoxylum oil and exposed to UV radiation. The alkylamides content was detected by using HPLC after different hours of radiation. The results indicated that hydroxy-α-sanshool under UV radiation decreased rapidly by 95.9% in 8 hours. Furthermore, the concentration and time obeyed the first order reaction rate equation C=490.68e^{-0.346 9t}, meanwhile it transformed into hydroxy-ε-sanshool, which was 8.56 times of its initial content after 3 hours. Moreover, another isomer hydroxy-β-sanshool kept deceasing under UV radiation，which indicated that UV radiation made a big difference on the numb-taste of Zanthoxylum bungeanum and its products.