The shopping trolley have been frequently used in our daily life. However, the hygiene condition of cart makes people worry a lot, especially the handle brothers. Nowadays, several methods have been proposed to clean the shopping carts but considered uneconomic and inflexible. In this study, we aim to design an integrated cart washing system based on a trailer applied to medium or small supermarket. This system should be more efficient, economic, easily to operate, safer and les water consummation. The integrated cart washing system has three basic functions of washing, disinfection and drying. The system is controlled by PLC program, all steps in the cleaning process are fully automatic insider the trailer and each component are adjustable according to various shopping carts. The system only requires one person to operate and it costs 30 seconds to wash a single cart, able to wash up to 120 cart/hour. Disinfection and drying steps provide high washing quality. Moreover, water-recycling design can save part of wasted water. The modelling and assembly was designed in Autodesk Inventor 2016, the hardware design circuit-writing diagram was performed in AutoCAD, the software design of Programmable logic controller (PLC) was made in STEP 7-Micro/Win. Theoretical calculation and simulation prove the safety and possibility of our system. We concluded that this system might have commercial interests in the market.