The invention relates to the technical field of embedded equipment, in particular to online diagnosis system and method of embedded equipment. The embedded equipment comprises one or more internal modules, and the system also comprises a diagnosis module which is arranged in the embedded equipment and used for receiving a diagnosis request of a user and returning diagnosis information. The invention is easy and convenient to operate on the site and is based on embedded software for online diagnosis, and the embedded software has the characteristic of real-time property. Meanwhile, when a system task is initialized, a class object is registered to a list, the related information of a diagnosis task can be directly extracted without wasting data transferring time so as to provide time guarantee for more rapidly acquiring diagnosis information needed by the system.