[Objectives]  To investigate the morphology, biological characteristics and life cycle of Discestra trifolii (Hufnagel). [Methods]  Laboratory observation. [Results]  The larvae of D. trifolii had 6 instars, and the duration of an entire generation was (44.27±3.10) d under laboratory conditions. The egg stage lasted for (4.02±0.35) d, and egg fertility was about 96.97%±1.20%. The larval stage lasted for (17.87±1.40) d, and the survival rate was 75.76%±6.94%. The pupal stage lasted for (10.48±0.80) d, and the survival rate was 93.86%±0.46%. The life span of adults was (12.62±2.82) d. [Conclusion]  The morphology and life history of D. trifolii will not only help to design efficient pest control methods, but also provide a theoretical basis for further study of this species.