[Objectives]  To clarify the biological characteristics of Neolycaena tengstroemi (Erschoff, 1874). [Methods]  The morphology, life history, and behavior, of N. tengstroemi were described systematically by field studies and captive rearing. [Results]  N. tengstroemi has one generation each year and overwinters as eggs in Ningxia. Larvae emerge from late March to mid-May. In early May, last instar larva begin crawling down to the litter layer or surface soil around host plant roots to pupate; the average length of the pupal stage is 15 days. Adults emerge in late May with a peak of emergence at the beginning of June. Adults lay eggs in early June and the duration of the egg stage is about 295 days. N. tengstroemi can both oversummer and overwinter as eggs in the soil or litter layer. [Conclusion]  The larvae of N. tengstroemi feed on flowers and leaf buds of host plants and are an important pest of Caragan korshinskii in Ningxia.