Abstract: In terms of a baroclinic quasi-geostrophic wave-filtering technique and through introducing a dimensionless parameter.η(Z),of condensation-released heat that indicates the CISK mechanism.a model is established for describing tropical atmosphere CISK-Rossby waves.At the same time.the model's analytical solution has also been obtained.Theoretical study shows that there is pronounced difference between CISK-involving Rossby waves and classic Rossby waves.and CISK-Rossby waves can better interpret some aspects of 30-50 day oscillation in the tropical atmosphere.