In the current study, different levels of L-cysteine hydrochloride (0.3, 0.6, 1.0, 1.5 g/kg) were incorporated in dough for the preparation of biscuits to investigate the effect of L-cysteine on the appearance and the content of four toxic aldehydes and fluorescent advanced glycation end products(AGEs) in biscuits. The results showed that the addition of L-cysteine hydrochloride brightened the color of the biscuits, and cause a slight decrease in pH values. The incorporation of L-cysteine hydrochloride significantly decreased the content of 5-hydroxymethyl furfural(HMF), 3-deoxyglucosone(3-DG), glyoxal(GO), methylglyoxal(MGO) and fluorescent AGEs in biscuits in a dose-dependent manner. The addition of L-cysteine at the level of 0.3 g/kg decreased the contents of HMF, 3-DG, GO, MGO and fluorescent AGEs in biscuits by 84.7%, 13.7%, 82.0%, 72.1%, and 8.9% respectively.