  The cosmological dynamics of minimally coupled scalar field that couples to
the background matter with thermal interactions is investigated by using
statefinder diagnostics. The time evolution of the statefinder pairs $\{r,s\}$
and $\{r,q\}$ are obtained under the circumstance that different values of
model parameters are chosen. We show that the thermal coupling term does not
affect the location of the late-time attractor, but exert an influence on the
evolution of the statefinder parameters. The most notable feature of the $r-s$
plane for the thermal coupling model which is distinguished from the other dark
energy models is that some part of the curve with thermal coupling can form a
closed loop in the second quadrant ($r>1,s<0$).
