To isolate and identify exosomes derived from periodontal ligament stem cells (PDLSCs) collected by ultracentrifugation. Using the limiting dilution technique, human PDLSCs were isolated and expanded. The cell culture supernatant of PDLSCs was collected. Exosomes were collected and purified with a ultracentrifugation method. Biological characteristics of exosomes derived from PDLSCs were measured by transmission electron microscopy (TEM), Western blot and nanosight tracing analysis (NTA). Exosomes could be successfully isolated from the supernatant of PDLSCs by a ultracentrifugation method. Under TEM, the PDLSC-derived exosomes exhibited elliptic or saucer-like shape and the central area had lower electron density than the circum area. The PDLSC-derived exosomes could express the common surface adhesion molecules CD9, CD63, CD81 and TSG101. NTA results showed that the collected exosomes had a size around (119±12.1) nm and an approximate concentration of (3.80±0.39)×108 particles/mL. Exosomes derived from PDLSCs can be collected by a ultracentrifugation method, which expresses common membrane proteins and morphological characteristics of exosomes.