Because of climatic changes and new tectonic movements,several sea and land evolutions occurred in the Bohai Sea area to result in the formation of subsurface brine.

In the south coast area of the Laizhou Bay, the Bohai Sea, a lot of subsurface brine is buried.

Analyzing the distribution, cause of formation and hydrogeochemistry character of coastal plain and inland subsurface brine in China we get the following conclusion: different cause of formation of subsurface brine bas different water quality character.

Chemical composition of underground brine in shore along Laizhou Bay;

Over 60 % of salt mine and hydrocarbon mine associates with underground brine (TDS≥50g/L)in Chi na.

cause of formation and chemical characters of the underground brine along Laizhou Bay.

In order to measure the radium isotopes in ground brine from the southern coast of Laizhou Bay,Bohai Sea,China,a series of laboratory experiments of simulating the ground brine were conducted using the Ba(Ra)SO4-coprecipitation method to pre-accumulate radium isotopes and the 226Ra and 228Ra radioactivi-ties were measured simultaneously with the gamma-ray spectrometry.

There is plenty of ground brine along the coastal line in Shandong Province.

This paper introduces the determination of brine composition by digital densimeter,also called reverse check of brine composition(the NaCl content in brine) by digital densimeter,which is a visible measure for brine density.