In this paper,Na+-Ti(SO4)2 method to detect residue of malachite green in grass carp was first established:Malachite green dissolved in concentrated sulfuric acid yellow,diluted significantly dark yellow,Ti(SO4)2 makes it fade,a white precipitate by adding Na +,malachite green residues based on the amount of precipitation for the quantitative.Optimization of experimental conditions,we choose pH=7.4,2.0 mol/L of titanium sulfate and sodium chloride,it can be effective in detecting residues of malachite green...