In this paper, it is shown that in the practical case of Ti≠ 0, for short wavelength modes (i.e. Sy≡ky2ρi2≥1), the usually adopted eigen-equation of drift wave is theoretically inconsistent, consequently, the inference that "The universal mode in fact, is stable" is also inappropriate. Under the condition of low magnetic field shear (Ls/rn >>[2Timi/Teme]1/2), a consistent eigen-equation of drift wave is deduced, which is valid for Sy≥1 as well as for Syi2), it can be shown that there is no unstable mode (i.e. there is no solution with γ>0). But if the correction term is taken into account, no definite conclusion about its stability can be obtained as yet.