High density brine drilling fluid has been widely applied in the high pressure and complex oil and gas fields. Effectively controlling high density brine drilling fluid loss is an important factor for reducing the reservoir damage and keeping well stability. Base on general drilling fluid formulations，the affecting factors of filtrate loss of high density brine drilling fluid were analysed through mass laboratory experiments. The results show that the main fctor was the content of caustic soda and bentonite, secondly the density and the shape of adding product. The combination of adding product is one of effective method to control the filtration property of high density brine drilling fluid. The results will provide reliable foundation for successful field application.