A phenomenon of combustion instability with frequency 106Hz was found in afterburner of a turbofan engine at testbed. The traditional approaches for excludingcombustion instability

such as resigning damping inner liner

changing fuel concentration distribution

appeared ineffective. Theoretical analysis and experimentalinvestigstion show that this combustion instability is a kind of heating choke due to aerodynamics of internal flow. This heating choke leads up to instableburning in overall afterburner. The conditions of emergence of this combustioninstability and approaches to eliminate it are elaborated in accordance with various test results.