The invention discloses a porous CeO2 nanomaterial preparation method and application in paper-based sensors with snowflake shaped Ag nanoparticles. Wax printing and laser cutter techniques are adopted for preparing a hydrophobic area, a semi-hydrophilic area, a hydrophilic area and a hollow passage on paper, and a paper chip is modified by printing corresponding electrodes on the paper and functionalizing operating areas. The obtained paper chip is folded to form a three-electrode system, and primary detection is performed. Pb<2+> activates DNA chain enzymes and catalyzes substrate chain breaking to promote fixation of a porous CeO2 nanomaterial on the paper-based sensors, and inhibition of electrochemical luminescence is substituted with the catalysis effect. The prepared paper chip is folded and subjected to secondary detection, and ultra-sensitive detection of a to-be-detected article is realized through luminous intensity difference of twice detection.