Quartz powder would release radical hydroxyl in phosphate buffer solution. In order to detect the quantity of radical hydroxyl with a quite low concentration, the present paper established a fluorescence method. According to the relationship between the concentration of 2-hydroxyl of terephthalic acid (HOTP) and fluorescence intensity at the wavelength of EXmax/EMmax=316 nm/422 nm, a working standard curve was constructed. Then through the filtrated fluorescence intensity obtained from the powder and solution system, cumulative concentration of ·OH can be measured indirectly. By repeating tests and analysis of five different experimental conditions of ·OH cumulative concentration, the minimum detection limit of the method reached 1.59×10-10 mol·L-1, with a relative deviation of 1.20%~7.89%, standard deviation was 1.09×10-9~2.17×10-9 mol·L-1 and the relative standard deviation was 3.5%~5.8%. The method features high accuracy and good repeatability performance. Compared to other quantitative studies, this method might be applied to test radical hydroxy produced in pH neutral solution systems. In addition, it has apparent advantages such as low detection limit, low cost, higher sensitivity, and better stability and reproducibility. That provides the means for the quantitative study of mixed systems consisting of quartz powder and phosphate buffered solution.