Silicon quantum dots (Si QDs) are usually smaller than 10 nm. They have drawn much attention from researchers because of their novel electronic and optical properties caused by quantum confinement effect and surface effect, which are different from those of bulk silicon materials. In recent years, Si QDs have been applied in the field of optoelectronics because of their novel electronic and optical properties, and a series of research progress have been achieved. The electronic and optical properties of Si QDs are overviewed. The use of Si QDs in optoelectronic devices such as light-emitting diodes, solar cells and photodetectors is introduced in detail. The performance of different types of Si QDs in optoelectronic devices is analyzed as well. It is believed that if continuous efforts in the research on Si QDs are made, Si QDs will play a crucial role in the innovation of optoelectronic devices in the future.