  In this paper we study the possibly existing anisotropy in the acceleration
expansion by use of the full sample of Union2 data. Using the hemisphere
comparison method to search for a preferred direction, we take the deceleration
parameter q0 as the diagnostic to quantify the anisotropy level in the wCDM
model. We find that the maximum accelerating expansion direction is
$(l,b)=(314_{+20^{\circ}}^{\circ-13^{\circ}},28_{+11^{\circ}}^{\circ-33^{\circ}})$,with
the maximum anisotropy level of $\delta
q_{0,max}/\bar{q}_0=0.79_{+0.27}^{-0.28}$, and that the anisotropy is more
prominent when only low redshift data ($z\leq0.2$) are used. We also discuss
this issue in the $CPL$ parameterized model, showing a similar result.
