I-deficient BiOI thin film was prepared via a facile solvothermal approach assisted with a ([C(6)Mim]l) ionic liquid and calcination. The glass plates were pretreated with high pressurized water to make the substrate surface rough. A thin layer of BiOI grew stably on the rough surface of glass substrate with uniformly assembled nanosheets. As the preparation process repeated, BiOI crystals continued to grow and the film became denser and thicker with larger surface area and pore volume. During calcination, a small portion of iodine was lost and iodine vacancies formed, leading to I-deficient BiOI. The produced iodine vacancies acted as traps for photogenerated holes. Consequently, the recombination of photogenerated electrons and holes were significantly inhibited. The film displayed an excellent photoelectric property and distinct photocatalytic degradation efficiency for bisphenol A (BPA), a typical endocrine disrupting compound (EDC), under simulated sunlight. The film also displayed very good durability and reusability. Without necessity to separate the photocatalysts from reaction solution, the as-prepared I-deficient BiOI thin film displayed a great potential for practical wastewater treatment. (C) 2017 Published by Elsevier B.V.