The effort to increase the growth and production of white oyster mushroom (Pleurotus ostreatus), it is necessary to add nutrients to sawdust which will be used as a growing medium for white oyster mushroom. One of the nutrients that need to be added is minerals including Ca (calcium) and Magnesium (Mg) contained in dolomite (CaMg(CO3)2) and macronutrients such as phosphorus contained in TSP fertilizer. The aim of this research to determine the effect of giving TSP fertilizer and dolomite on mushroom growing media (baglog) on the production of white oyster mushrooms. This research was conducted in September 2019 to March 2020 in the village, of, Lau Bakeri village, Kutalimbaru District, Deli Serdang Regency The research used a factorial randomized block design with two treatment factors, namely TSP fertilizer (control, 1.2%, 2.4%) and dolomite (control, 1%, 2%, 3%. The results showed the application of triple super phosphate fertilizer and dolomite did not significantly affect to all observation parameters of white oyster mushrooms, but the interaction between triple super phosphate fertilizer and dolomite was able to accelerate the age of harvesting, increase the fresh weight of mushrooms in the first and second harvests and the number of mushroom caps at the third harvest.