Abstract: A high-sensitivity, high-selectivity and portable detection method for trace uranyl ion is described. The method has an ultralow detection limit of 11 pM/2.6 ppt and is useful in precise monitoring of the uranium content in agricultural and sideline products, foods, environments and so on. The test instrument is miniaturized and low in cost to achieve high-precision portable measurement in the field. A conjugated polymer with aggregation-induced emission (AIE) activity is synthesized, and prepared into Pdots, and a uranyl-responsive electrochemiluminescence (ECL) probe is developed by modifying the Pdots with DNA or RNA, which serves as an adsorption ligand of uranyl ion. The probe exhibits good biocompatibility. The ECL technology can be used in uranyl ion detection and the method has extremely high sensitivity. A uranyl ion probe with AIE activity is also disclosed, which can be applied in portable precise monitoring of trace uranyl ion by means of the ECL technology.