We report on the successful fabrication of highly branched CuS nanocrystals by laser-induced photochemical reaction.Surprisingly,the single-crystalline nature with preferential alignment of the (107) orientation can be well improved during the moderate growth process.The branch length drastically increases from about 5 nm to 6 μm with an increase of photochemical reaction time (0-40 min).The absorption spectra of as-prepared CuS nanodendrites show that localized surface plasmon resonance (LSPR) peaks can be modulated from about 1037 nm to 1700 nm with an increase of branch length.Our results have a promising potential for photodynamic therapy and biological imaging application.