The invention discloses an e-commerce platform transaction system and method based on a mobile terminal. The e-commerce platform transaction system comprises a merchant client, a user client and a background server, the merchant client is provided with an entity merchant joining module, an online store management module, a commodity management module and an address management module; and the userclient is provided with a commodity selecting and purchasing module, a 3D virtual try-on module, a shop route prompting module, a payment module, a commodity distribution module and a personal information input module. The operation mode provided by the invention is different from a traditional in-store consumption mode and is also different from a traditional e-commerce mode, takes a mobile terminal as a carrier and joins an offline clothing physical store to an online e-commerce platform; the commodity discount information, online 3D virtual try-on and online convenient services of the storeare published online in real time through the platform, and meanwhile, the try-on, purchase, home delivery, exchange and other services of the physical store corresponding to the online are providedoffline.