As semiconductor nanocrystals, colloidal quantum dots (CQDs) are widely used as gain materials for micro/nanoscale lasers owing to their advantages of high quantum yields (~100%), tunable emission wavelengths, excellent stability, high refractive index, solution processability, and low-cost synthesis. Based on nanoscale sizes (2--20 nm) and solution processability, CQDs can construct high refractive index micro/nanoscale structures through self-assembly methods. Here, three kinds of CQD micro/nanoscale lasers are summarized based on manufacturing methods of CQD resonators, and their characteristics are discussed in details. In addition, the on-chip integrations of CQD lasers and waveguides are also introduced. Finally, the outlook for the development of CQD lasers and its on-chip integration in photonic integrated circuits (PICs) is provided.