Blue light can regulate the secondary metabolites and sporogony in Monascus, however, the mechanism is still unclear. Aminophylline is a kind of inducer of adenosine 3′,5′-cyclization monophosphate -cAMP- intracellular. To study the role of cAMP on the sporulation and citrinin production by blue light induced Monascus, citrinin production and number of spores in fermentation broth were detected after aminophylline added into the culture medium. When the content of aminophylline reached 10mmol/L, citrinin production and the number of conidium increased by 190 and 297 times, respectively. When the concentration of aminophylline got to 15mmol/L, the number of ascospores increased by 284 times. This result corresponds to the changes of citrinin production and sporulation in Monascus affected by blue light. It is presumed that blue light affects the spore production and metabolic regulation of citrinin in Monascus is possibly via the cAMP signaling pathway.