Chrysocolla is a kind of copper oxide mineral which was difficult to float. In this study, Diethyldithiocarbamate (DDTC) was employed to modify the surface of chrysocolla to improve its xanthate adsorption and floatability. Flotation experiments showed that the DDTC exhibited ability to activate rather than acting as a collector for chrysocolla flotation. After DDTC activated, Chrysocolla can be effectively recovered by xanthate. The activation mechanism of DDTC was investigated via Fourier transform infrared (FT-IR) spectroscopy and X-ray photoelectron spectroscopy (XPS). During the activation, DDTC bonded to the surface copper atoms of chrysocolla, and more Cu(II) species on the mineral surface were reduced to Cu(I) species, which caused the formation of larger amounts of Cu active sites as –N–C(=S)S–Cu(II)– and Cu(I) species. The results of the adsorption tests and zeta potential measurements revealed that the DDTC-modified mineral surface reinforced adsorption of xanthate ions, thereby improving the chrysocolla floatability. Therefore, the Cu ions double interaction of DDTC and xanthate on the chrysocolla surfaces enhanced the strength and stability of the hydrophobic layer, resulting in an enhanced hydrophobization of the chrysocolla for its flotation.