An assemblable wireless Internet connected apparatus and an integrated function system are provided. The integrated function system includes a function-extended apparatus and the assemblable wireless Internet connected apparatus. The function-extended apparatus includes a first communication interface complied with USB and UART standards. The assemblable wireless Internet connected apparatus includes a wide area network wireless communication module, a second communication interface and a computation-and-controlling unit. The wide area network wireless communication module connects the Internet. The second communication interface is used for engaging with the first communication interface and is complied with the aforementioned two standards. The computation-and-controlling unit communicates with the function-extended apparatus through the second communication interface, and transmits data from the function-extended apparatus to Internet through the wide area network wireless communication module. Accordingly, a separable product with heterogeneous network integration and a novel development way are provided.