The invention discloses a primer, a kit and a method for detecting Escherichia coli type I Shiga toxin by PSR. The present invention designs primers for detecting Escherichia coli type I Shiga toxin for the heterosexual target sequence stx1 of type I Shiga toxin, and the primers include detection primer Ft and detection primer Bt, acceleration primer IF and acceleration primer IB, and its nucleotide The sequences are shown as SEQ ID NO.1-SEQ ID NO.4. The present invention also provides a kit for detecting Escherichia coli type I Shiga toxin by PSR, comprising the above-mentioned primers, Bst DNA polymerase, and a mixed solution of calcein and manganese chloride, capable of detecting Escherichia coli type I Shiga toxin For the detection of polymerase helical reaction, the result can be judged by the naked eye by directly using fluorescent dyes to develop color. The operation is simple and fast, and the detection cost is low, which is suitable for on-site detection applications.