The present invention discloses a method for detecting heavy metal content based on homogeneous time-resolved fluorescence, comprising: stirring and mixing Eu<3+>-containing europium cryptate, 300 nM of a 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide solution, and 300 nM of a N-hydroxy sulfosuccinimide solution to form a first activation mixed solution; performing a coupling reaction for 50 nM of papain and the first activation mixed solution to form Eu<3+> salt modified papain; stirring and mixing XL665, a 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide solution and a N-hydroxy sulfosuccinimide solution form a second activation mixed solution; performing a coupling reaction for 50 nM of papain and the second activation mixed solution to form fluorescent dye XL665-modified papain; and mixing the Eu<3+> salt modified papain and the fluorescent dye XL665-modified papain to form a fluorescence detection solution. The method of the invention has the advantages of simple operation, fast speed, high sensitivity, wide linear range, low cost, and achievement of on-site detection.