The invention discloses a benzene sulfonic amide compound shown in a formula 5, a preparation method thereof, a labeled precursor of the benzene sulfonic amide compound used as a PET molecular imaging probe and the application of the labeled precursor to the preparation of the benzene sulfonic amide compound. The preparation method is simple and has no particular requirements for high-temperature, high-pressure or sensitive reagents. The invention also discloses a midbody compound which is shown in a formula 4 and used in the preparation method of the compound and the preparation method of the midbody compound.