In this research, the flotation performance and adsorption mechanism of tert-butylsalicylaldoxime (TBSA) to malachite were studied by micro-flotation, contact angle, zeta potential, FTIR and XPS analysis. The result of micro-flotation tests indicated TBSA yielded high malachite recovery and satisfied selectivity against calcite or silica at pH 9.0-10.5. The contact angle results inferred that the hydrophobicity of malachite surfaces was improved after TBSA modification. The results of zeta potential suggested that TBSA might chemisorb on malachite surfaces. XPS and IR spectrum analysis confirmed that the O atoms in C=N-OH group and benzene ring fixed with Cu species on malachite surfaces through C-O-Cu, N-O-Cu and d-p pi bond respectively.