A three-channel high-precision optical detecting system for lang cancer marker CYFRA21-1is described.This system is based on the magnetic enzyme-linked immunoassay,depends on the skillful mechanical desi gn and precise controlling system,uses FPGA to count the high-frequency pulse and NIOS to control the whole system,an d achieves the quantitative detection of CYFRA21-1with the help of my own PC software.On the premise of high precision ,three channels can be used in the same time,which can increase the efficiency of detection significantly.Aft er experimen tal verification,the interference among the three channels is little and the consistency is good,and the relative deviation is lower than 1%.The CYFRA21-1sample with concentration of 2－100ng/mL was measured and the correlation coefficient betwe e n CYFRA21-1concentrations is 0.979.This system is small,has high sensitivity a nd short detecting time,so it could be a powerful tool for the rapid disease marker detection.