A facile synthetic strategy to prepare single-sized colloidal CdTe assemblies with bright band gap emission is described in this letter. In contrast to traditional approaches, the preparation of trioctylphosphine telluride (TOPTe) was not required for this synthesis, and our approach follows a one-step reaction. The CdTe magic-sized quantum dot (MSQD) assemblies were sequentially grown in this approach, and the thermodynamic equilibrium of CdTe MSQDs sequential growth was proposed.