An organic reagent-assisted method has been developed for the synthesis and assembly of copper sulfide, cadmium sulfide and silver sulfide nanocrystallites at low temperature under hydro- or solvothermal conditions. Nanowire-like aggregates (with an average diameter of 120 nm and length of 2 μm) assembled by digenite phase copper sulfide nanoparticles, nanotube-like aggregates (with diameters ranging from 40 to 200 nm and lengths from 400 nm to 4 μm) and nanovesicle-like aggregates (with size ranging from 50 to 180 nm) assembled using djurleite phase copper sulfide nanoparticles have been obtained using triethylenediamine, tramethylethylenediamine and di-n-butylamine as the linking agents, respectively. A cetyltrimethyl-ammonium bromide-assisted solvothermal process with CdCl2 and thiourea as the reactants and ethylenediamine as the solvent has been proposed to control the length of the CdS nanorods from 300 nm to 4.5 μm and construct novel CdS nanorod-based structures, including polydentate wire-like architectures and polydentate sphere-like architectures composed of dozens of CdS nanorods of 10 nm in width and 100 nm in length. A CH3(CH2)11SH-template method has been adopted to realize the synthesis and the simultaneous assembly of silver sulfide nanocrystallites with AgNO3 and Na2S as reactants. By changing the reaction temperature and the dodecylthiol concentration, two-dimensional orthogonal and hexagonal-like ordered silver sulfide nanoparticle arrays and quasi-orthogonal silver sulfide nanorod arrays can be obtained. This organic reagent-assisted route is very simple and can be extended to the synthesis and assembly of other semiconductor sulfide nanocrystals.