  Pulsar glitches are the sudden increase in their spin frequency, most
accompanied with a long timescale recovery process. A permanent shift would be
remained in the first order derivative of spin frequency with time. Relevant
data fitting research about this persistent shift was performed in this essay,
we have found a more suitable fitting strategy by choosing a fitting function
form $k\ln(ax + b)$ and demonstrated that would be more meaningful in pure
mathematical aspect in describe the correlation between the time scale of
Delayed-Spin-Up $\tau_{d}$ (so as the persistent shift $\Delta \dot{\nu}_{p}$)
and glitch size $\Delta \nu$.Some possible physical ideas about this fitting
also have been presented while the clear physical mechanism behind this
strategy still remain unknown.
