Abstract: The Procedure determining the cocentrations of total rare earth and their determination photospectrometrically with a new reagent, tribromochlorophosphonazo (CPA-tB), that is 7-1-(2,4,6-tribromo-phenyl) azo-2-1-(2-phosphono-4-chloro-phenyl) azo-chromotropic acid, in high-level liquid waste and some charactors of CPA-tB are studied. CPA-tB and its complexes of rare earth elements are stable in the glycol-H_2O system. Adding glycol shifts the absorption spectrum to left and increases the molar extinction coefficient. The molar extinction coefficients are respectively 7.16×10~4(Y), 11.9×10~4(La),11.7×10~4(Ce,Pr),11.9×10~4(Nd), 11. 6×10~4(Sm,Eu), 11.4×10~4(Gd) and 11.4×10~4 (RE) in the glycoI-H_2C_2O_4-H_3PO_4-H_2O system at 643 nm. Th interferes severely the determination of total rare earth, and other elements, U(<100μg), Al(<20μg),Fe(<400μg),Ni,Zr(<100μg respectively) and some anions, MoO_4~(2-)(<2800μg), EDTA(<20mg), F-(<266μg), Cl-(<110 mg), NO_3-(<150mg) do not interfere it.