Over the last decades, halide materials, represented by organic-inorganic hybrid perovskites, have emerged with great potential for the next-generation photonic and optoelectronic devices. In particular, their excellent photonic and optoelectronic properties can be further engineered by chemical compositions, material sizes, device structures, external fields and so on. More recently, tuning of dimensionality plays a significant role in promoting the properties of organic-inorganic hybrid perovskites. Originating from shape diversity and quantum confinement effect, the emerging different forms of perovskites, such as nanocrystals, nanowires/nanorods, nanoplatelets/nanosheets and ultra-thin films, have heralded new opportunities for novel physical phenomenon and high-performance devices. Particularly, the ultra-thin organic-inorganic hybrid perovskites, which combing the advantages of two-dimensional (2D) materials and organic-inorganic hybrid perovskites, are attracting more interest thanks to the exotic and unique properties. Considering the ultra-smooth surface and interface, ultra-thin organic-inorganic hybrid perovskites based heterostructures with van der Waals contacts can be artificially designed without considering the lattice matching. More novel properties will emerge and can be easily engineered by the strong interface coupling in ultra-thin organic-inorganic hybrid perovskites stacks. By flexible design of heterostructures based on ultra-thin organic-inorganic hybrid perovskites and their integration with diverse 2D materials, it offers many possibilities to discover new properties and device functionalities within the 2D family in the fields of green energy, sensor, integrated circuit and so on. In this presentation, I will introduce my achievements in the fields of ultrathin 2D organic-inorganic hybrid perovskites, including the materials design and preparations, heterostructure constructions, optical properties explorations and optoelectronic device designs.