  The variation mechanism of blazars is a long standing open question. The
polarization observation can provide us with more information to constrain
models. In this work, we collect the long term multi-wavelength data of AO
0235+164, and make correlation analysis between them by using the local
cross-correlation function (LCCF). We found that both $\gamma$-ray and the
optical {\it V}-band light curves are correlated with the radio light curve at
beyond 3$\sigma$ significance level. The emitting regions of the $\gamma$-ray
and the optical coincide within errors, and locate at {$6.6_{-1.7}^{+0.6}$} pc
upstream of the core region of 15 GHz, which are beyond the broad line region
(BLR). The color index shows the redder when brighter (RWB) trend at the low
flux state, but turns to the bluer when brighter (BWB) trend at the high flux
state. While, the $\gamma$-ray spectral index always shows the softer when
brighter (SWB) trend. We propose that such complex variation trends can be
explained by the increasing jet component with two constant components. The
{optical} PD flares and {optical} flux flares are not synchronous. It seems
that one flux peak are sandwiched by two PD peaks, which have inverse rotation
trajectories in the $qu$ plane. The helical jet model can schematically show
these characteristics of polarization with fine tuned parameters. The change of
viewing angle is suggested to be the primary variable which lead all these
variations, although other possibilities like the shock in jet model or the
hadronic model are not excluded completely.
