With the model of an axially symmetric rotor plus two quasi-particles, the signature inversion (SI) in two odd-odd nuclei 102Rh and 98Rh in the mass region A=100 is studied. The calculated result shows that the possible SI mechanism, which has been confirmed by the calculation of odd-od d nuclei in the A=160 and A=80 regions (i e, the competition between the n-p interaction and the coriolis force in low K space) is also appropriate for odd-odd nuclei in the A=100 region. This seems to indicate that there mi ght be a universal mechanism of SI in odd-odd nuclei for different mass regions.