A new scanning system is developed,which is a new biosensor for the immunoassay by using the label of up-converting phosphors (UCP),which is different from traditional methods and suitable for multiplexing and quantitative analysis. The system scans the strip point by point in order to record all the information on it,then figures out the concentration of the biological molecular from the content of the UCP on the test strip. It is effective to take precise detection of micro-immunoreaction to the degree of hundreds ng/ml with fine stability,which meet the requirements of the immunoassay.