Based on the development of event stratigraphy, this paper firstly suggests a series of event stratigraphic units which contain Event Surface, Event Bed, Event Zone, Event Association and Event Gathering and their meaning and characteristics have been determined. New event stratigraphic units are applied in the research of Event Group across the Sinian-Cambrian Boundary of Middle Yangtze Platform. The studies suggest that there are two Event Surfaces, i.e. biomass extinction and flooding Event Surfaces, one Event Bed, namely clay Event Bed, four Event Zones, i.e. sea-level dropping, turbidity, sea-level rising and anoxic Event Zone, three Event Associations, namely sea-level dropping-turbidity, extraterrestrial impacting-biomass extinction and sea-level rising-anoxic Event Association across the Boundary. They form an Event Gathering. The oil-bearing analysis of Event Strata indicates that sea-level rising-anoxic Event Association is favorable to producing oil, while the sea-level dropping- turbidity Event Association may be favorable to reserving oil and gas.