Nowadays, the mean load spectra ,which has a defect of long fatigue period,is always used in fatigue test for aircrafts.Use the severe load spectra instead,the test time can be greatly reduced.To meet the demand of full-scale fatigue test for life evaluation and respond to the requirements of aircraft strength criterion at home and abroad, this paper combines task analysis method with flight subject statistic analysis method, and develops severe load spectra for airplane structure of every subject and all subjects based on take-off and landing data of a instructional airplane . The process of spectra generation has been arranged and completed.The load spectra are determined for weighted mean, the meen plus 1 standard deviations,the mean plus 2 standard deviations,and for the 90%probability/95% confidence level.The approach to choose representative take-off and landing of severe load spectra is presented by equivalent damage calculation and statistic analysis .after the equivalent damage distribution has been examined by contrasting through K-S method.