In this paper

the coupled-mode equations for chirowaveguides filled with homogenoous and isotropic chiral media arc derived

starting from Maxwell’s equations and the constitutional relations of chiral media. For the hybrid coupled modes existing in chirowaveguides

we get the general expressions of the coupled-mode equations

then under the condition of weak-coupling

we point out the idea of solving the coupledmode equations by the perturbation theorems

so a new theoretical aprroach has been formulated to analyze the discontinuily in chirowaveguides.