As high-rise buildings become more and more popular in urban areas, their exterior cleaning has turned into an essential but also difficult and risky task. In order to enhance its efficiency and reduce the labor cost as well as the risk to the cleaning personnel, a smart cleaning robot has been developed to meet these demands. It is feasible to versatile working environments like different commercial and residential buildings. The excellent maneuverability of this cleaning robot ensures the best cleaning of any kind of architectural exterior materials. Through a modular design, users can choose the most suitable cleaning mode for efficient cleaning with least water need. In addition, all components are replaceable while damaged. This has guaranteed a longer lifespan of the product and made it environmentally friendly. The locomotion of the machine is achieved by the boom and guide rails installed at the rooftop as well as the hanging cables. With the help of the embedded obstacle-crossing solution, it can confront any irregularity of the building exterior and reach anywhere on the periphery to accomplish the cleaning process. The base of cleaning robot features the functions of water recharge and brush cleaning. The fans on both sides of the machine assist in adhering it to the wall of the building so as to make it stable during the operation. Users can have the full control of the machine and real-time monitoring of the cleaning progress through the mobile app to ensure an efficient execution of building exterior cleaning operation.