Gestational diabetes mellitus (GDM) is a conditionaldiabetes which is defined as any degree of glucoseintolerance or high blood glucose levels during any phase ofpregnancy. It causes chronic severe damage to health of thepregnant women and their offspring. In this study, we aimedto study the protective effects of Cryptotanshinone on GDMrelatedimpairments. We measured blood glucose levels,serum insulin levels, biochemical indexes, oxidative stress,inflammation and the activation of NF-κB signaling pathwayin the blood and placenta of GDM mice. It is found thatCryptotanshinone significantly decreased blood glucose levels,oxidative stress, inflammation and NF-κB signaling withan increase of serum insulin levels in the placenta and bloodof GDM mice. Taken together, Cryptotanshinone effectivelyameliorated GDM, which suggested that Cryptotanshinone could be served as a promising therapeutic drug for GDMpatients.