The utility model relates to a special-purpose magnetic measuring ruler. The special-purpose magnetic measuring ruler comprises a ruler plate provided with a marking scale. The measuring ruler is characterized in that the two ends of the ruler plate are respectively provided with a round hole; a glass plate connected with the ruler plate in a clamping way through the round holes is arranged on the ruler plate; magnifiers are uniformly distributed on the glass plate; and a permanent magnet is arranged on the back of the ruler plate. By arranging the permanent magnet on the back, the measuring ruler plate can be attracted to a target part. Meanwhile, the glass plate arranged on a local part of the ruler plate and provided with the magnifiers can make the numbers on the marking scale of the ruler plate magnified at intervals. When taking notes, people can clearly get the accurate number values by only holding a recording folder and a writing pen. When recording through a camera, people are also enabled to freely choose a shooting position and shoot photos attentively. Clear photos can be thus acquired. Therefore, the working efficiency and the recording qualities are improved. The special-purpose magnetic measuring ruler which has the characteristics of simple use and flexible and convenient operations can reduce required workers, lower the working cost and alleviate work risks when used for on-site recording.