The inflatable lunar habitat, known for its high packaging efficiency, light weight, and low transportation costs, is considered one of the most promising designs for lunar habitation. The harsh lunar environment faced by lunar habitats is reviewed, and a classification of typical flexible inflatable lunar habitat design schemes is provided, both domestically and internationally. The advantages and disadvantages of different flexible inflatable lunar habitat construction plans are compared, and existed typical inflatable lunar habitat designs are summarized. Finally, based on the requirements for lunar habitats, key technologies for flexible lunar habitats are summarized, including thermal protection technology, micrometeoroid impact protection technology, and inflatable structure health monitoring technology. This paper offers a reference for the design of inflatable lunar habitats and construction of Chinese lunar base in future.