An in situ microwave-assisted Fenton-like oxidation has been developed for detemplation of the nanozeolite β without any pretreatment. The influencing factors on the removal of structure-directing agents (SDAs) in the nanozeolite β, such as the composition of Fenton-like reagents (pH, H₂O₂/TEA⁺, Fe³⁺/H₂O₂) and microwave operation conditions, are investigated, to find that the SDAs in the micropores and solution of the as-prepared nanozeolites could be completely eliminated within 15 min. In comparison with those obtained by the traditional high-temperature calcination, the Fenton-treated nanozeolite particles not only preserve their monodispersity and large external surface area, but also avoid the formation of extra-framework aluminum, which renders an enhanced catalytic performance in fructose dehydration.