Commonly sampling media in gold geochemical exploration include rock, stream sediment, soil, plant, and gas. In recent decades, calcrete has been successfully used as a sampling medium in geochemical exploration of concealed gold deposits in semi- arid and arid areas in Australia. In this paper, the theory and advances in the use of calcrete as the sampling medium in geochemical exploration of concealed gold deposits are summarized. This method is based on the high correlation of gold with calcium in the soil profile. A probable explanation for the genetic mechanism is as follows: the weathering of primary gold deposits or mineralization forms various gold complexes, nano gold, and its colloids. Then, the dissolved gold and nano gold can be migrated from deep to shallow horizon by evaporation and transpiration, plant roots, electrochemistry, earth gas, seismic pumping, and other functions. In a wet sub- period, gold could form gold amino acid complex or gold colloid with the help of microbial breakdown of plant organic material. There is no correlation between gold and calcium in soils at early time; in drying sub- periods, the destabilization of gold amino acid complex or gold colloid gold results in co- deposition of gold and calcium. Finally, combined plant- microorganism- climate effect leads to form gold anomaly in calcrete. Notably, the research in China suggested that the contents of gold and calcium are not positively correlated since the presence of clay would promote gold enrichment, and the presence of plaster and calcium carbonate would prompt gold depletion; in addition, topography will also affect the formation of gold anomaly in calcrete. Therefore, it still needs to be tested if the method could be applied outside Australia.