The invention relates to a method for rapid detection of a target nucleic acid amplification product while preventing cross-contamination between target nucleic acid amplification products and avoiding false positives, comprising the steps of: a) leaving the reaction tube unopened after the amplification reaction is finished, so as to prevent the target nucleic acid amplification product from leaking out and resulting in contamination; b) placing the unopened reaction tube inside an enclosed unit, making the target nucleic acid amplification product be transferred to a test strip from the reaction tube in a physically enclosed environment; c) performing detection in a visual read-out manner, and determining the result; d) discarding the enclosed unit in a safety place as a whole without opening it after the detection. The invention also relates to a totally enclosed unit for detecting a target nucleic acid amplification product, and still relates to applications of the totally enclosed rapid detection unit in detection of infectious pathogens, food industry, agriculture, livestock husbandry, customs quarantine control, and determination of DNA.