The existing research on flight test risk control techniques related to flutter/ASE test is not systematic, have limited consideration of civil fly-by-wire aircraft characteristic and onboard flight test engineer. The more systematic study was proposed including theoretical evaluation, instrumentation, flight test technique, risk analysis, mitigation measures and emergency procedures covering flight test preparation and test conduction. Three hazards were identified including flutter/ASE unstable, adverse handling qualities and local structure damage. A technique was proposed that onboard flight test engineer cutoff excitation when vibration exceed limit. A dedicated monitor software was developed to calculate damping ratio and ASE margin in telemetry. A civil aircraft flight flutter/ASE test shown that the proposed technique reduces flight test risk and cost effectively, manual cutoff excitation within 1 second protect aircraft structure, real-time analysis can provide stability margin timely and improve test efficiency.