The coupled dark energy models , in which the quintessence scalar field nontrivially couples to the cold dark matter , have been proposed to explain the coincidence problem .
In this paper we study the perturbations of coupled dark energy models and the effects of this interaction on the current observations .
Here , we pay particular attention to its imprint on the late-time Integrated Sachs-Wolfe ( ISW ) effect .
We perform a global analysis of the constraints on this interaction from the current observational data .
Considering the typical exponential form as the interaction form , we obtain that the strength of interaction between dark sectors is constrained as \beta < 0.085 at 95 \% confidence level .
Furthermore , we find that future measurements with smaller error bars could improve the constraint on the strength of coupling by a factor two , when compared to the present constraints .