The invention discloses a fluorescent probe for detecting various metal ions in water, and a preparation method and application thereof. The probe is made up of symmetrical tetramethyl cucurbit [6] uril and trans-4-4(Dimethylamino)styryl-1-methylpyridine iodine. The preparation method comprises the following steps: dissolving tetramethyl cucurbit [6] uril in water to obtain a solution A; dissolving trans-4-4(Dimethylamino)styryl-1-methylpyridine iodine in water to obtain a solution B; and mixing the solution A and the solution B, and reacting at normal temperature to obtain the probe. The probe is mainly used to detect caesium, strontium, barium, iron, chromium, mercury, europium,thulium and/or ytterbium ions in water. The probe disclosed by the invention can be used to detect various ionsof caesium, strontium, barium, iron, chromium, mercury, europium,thulium and/or ytterbium in water, and has the characteristics of high sensitivity, low detection cost, simple sample processing, convenient operation, rapid determination and real-time detection.