he reversed-phase paper chromatography with di-isoamyl methylphosphonate(DAMP) as the stationary phase and solutions of various concentrations of nitric acid,hydrochloric acid,perchloric acid and sodium nitrate as the efliuent were investigated,The R_t values of UO²⁺²,Th and many radio-nnolides on paper treated with 0.1M DAMP in benzene were obtained.According to the R_t values and selecting the suitable mobile phase,good results were obtained for the separation of UO²⁺²-Th,⁹⁰Sr-⁹⁰Y,⁹⁵Zr-⁹⁵Nb,²¹⁰Pb-²¹⁰Bi-²¹⁰Po and the mixture of UO²⁺²,Th and some radio-nuclides.The noticeably different R_t values between macro-concentration and trace level of some heavy metal ions were revealed.