The research on the reaction of the metal complex (BPR-Zn2+) as spectrum probe for protein in alkaline medium was conducted in this paper. The experiments indicate that the ternary complex between BPR-Zn2+complex and protein could be used as a method for protein determination. The reaction conditions, interference materials and sample were studied. A dual-wavelength method is applied to obtain the binding number of spectroscopic probe bound on molecular protein and the reaction mechanism was studied.