Strata completeness refers to "the fraction of time intervals of some specified length (t) that have been preserved." Since the 1780s, it has been widely accepted that most stratigraphic sections are riddled with gaps and are discontinuous over a range of temporal scales. Recognizing stratal disconformities or hiatal surfaces, and quantifying the stratal completeness of carbonate/clastics are essential for: (1) adequately constructing time series of palaeoclimatic and palaeobiologic changes, (2) understanding the impact of orbital forcing and sea-level changes on the geochemical signals within the strata, (3) enhancing interpretations of time series of depositional settings and sedimentary processes, and (4) hydrocarbon explorations. Although many researchers have attempted to delineate strata completeness using different approaches, such as statistical method, dating techniques, physical modeling, stochastic modeling and stratigraphic forward modeling, there are still some unresolved issues relating to the topics, and especially regarding quantitative determination of strata completeness and key factors affecting it.