By using the NCEP/NCAR-FNL reanalysis data, historical weather graphs and the Tibetan Plateau vortex and shear line year books, activities of the Tibetan Plateau vortex (TPV) during the period of 1998 to 2016 are analyzed. The persistence (longer than 96 hours) and short-time maintenance (shorter than 30 hours) of the Tibetan Plateau Vortex examples after they moved out of the plateau, the corresponding atmospheric circulations, cold air activity characteristics and potential vorticity are investigated. The background fields and cold air activities associated with the long-time persistence of TPV (LTPV) and short time maintenance of TPV (STPV) are analyzed. The influences of cold air activity and high-level fronts to the two types of TPV are also revealed. Results are as follows. (1) The LTPV is strengthened and persisted due to the influences of obvious cold air, and the STPV is under no influences of obvious cold air. The LTPV is often located in a deep trough with obvious cold trough behind the trough and the subtropical high is leaning to the south. The STPV is usually located in a split trough with cold tongue and the subtropical high is leaning to the north. This means that the weather system that influences the TPV is strong. The distinct cold trough behind the height trough and the northward-leaning subtropical high are important conditions for the LTPV. (2) The LTPV is not only influenced by relatively strong cold advection, but also located in the long and narrow area where the dry cold air and warm wet air converge. This condition easily leads to convective instability and low vortex turbulence, which is favorable for the reinforcement and persistence of the LTPV. The STPV's condition is far less than that of the LTPV. (3) The LTPV is influenced by cold air from two different directions and usually accompanied with two high potential vorticity centers; the STPV only has one high potential vorticity center, and the potential vorticity value is lower than that of the LTPV. The LTPV has stronger baroclinity than that of the STPV. Furthermore, the LTPV is often accompanied with consistent and strong high-level jet stream, which leads to the transfer of the 200 hPa high potential vorticity to the TPV when strengthening and expanding to the east and pushing to the south. But the STPV corresponds to a weak and straight westerly jet stream, which can only transfer high potential vorticity from 400 hPa to the TPV. (4) The mechanism for cold air to influence the maintenance of TPV is that the cold air strengthens the corresponding weather systems, increases the baroclinity and convective instability of the TPV. And the cold air enables the high level potential vorticity to spread to the low level area close to the TPV and increases the positive vorticity in the TPV region, which increases vertical vorticity and strengthens the TPV.