The invention relates to a probe for detecting transgenic plants, a surface plasmon resonance biosensor and a method for detecting the transgenic plants. The nucleotide sequence of the probe is a sequence shown in SEQ ID NO:1. The probe and the surface plasmon resonance biosensor containing the probe can specifically detect a cry1A gene, and have the advantages of high detection sensitivity, no needing of marking of samples, regeneration and easy use. The sensor overcomes the disadvantages of long time consuming, high cost and non-repeatable detection of a traditional transgenic detection PCRmethod, and the practice proves that a degenerate single-stranded nucleic acid probe can also be designed for transgenic detection with regard to different DNA sequences between species, and large-scale and high-throughput detection of various insect-resistant (cry1A) genes can be achieved.