The elimination of malachite green (MG) in different groups’ tilapia (Oreochromis  spp.) muscle was studied, using different sizes of (150 ± 20)g and (45 ± 10)g, different cultivating conditions of freshwater and 15‰ of salt, different concentrations of medicated bath of 0.5mg·L-1 and 2mg·L-1, respectively, in order to investigate residues of MG and to monitor the use of MG in fish. The former deal was simple, fast, without liquid-liquid extraction and solid-phase extraction, greatly reducing costs by pure organic solvent extraction target. The results showed that the entire MG group was not detected up to day 60, but LMG (leucomalachite green) still could be detected so that LMG had slower metabolism than MG. Large-sized tilapia MG and LMG had metabolism faster than the small tilapia. The residues of MG and LMG were different under different cultivating conditions; at the same time MG in the salt cultivating condition had more residue than that in freshwater, but LMG was just the opposite. MG and LMG in the tilapia muscle by high concentration of medicated bath were higher than those by low concentration of medicated bath, and the residue in the former lasted a long time. The Lower case of actual situation, the comparison of different experiments under the conditions of malachite green residues of metabolism, in order to solve China’s fishing industry problem, has provided a basis for reference for the future development of long plagued quality and safety issues.