  In non-canonical two-field inflation models, deviations from the canonical
model can be captured by a parameter $\xi$. We show this parameter is usually
one half of the slow-roll order and analytically calculate the primordial power
spectra accurate to order $\xi^2$. The super-horizon perturbations are studied
with an improved method, which gives a correction of order $\xi^2$. Three
typical examples demonstrate that our analytical formulae of power spectra fit
well with numerical simulation.
