A fast seed activity analyzer(FSAA) based on the detection of ultra weak chemiluminescence(UCL) was developed.Using the analyzer,vigor of seeds could be quantified with the seld developed softward.High sensitivity and good signal to noise ratio was achieved by use of single photon counting technique.This instrument can distinguish the rice seeds that are different one season in aging at least.The EZ USB AN2131Q chip was engaged to dominate control and data acquisition of the analyzer.The universal serial bus(USB) and its advantages in data acquisition were also introduced in this paper.