The invention discloses an aerial-photogrammetry-based existing railway line plane midline production method, which comprises the following steps: office work and field data acquisition, office work acquisition midline checking and connection, automatic characteristic point projection coordinate calculation, characteristic point mileage mutual checking and sectionalized adjustment section selection, sectional mileage coordinate adjustment calculation and existing line plane midline generation. According to the existing railway line plane midline production method, shortcomings of existing line operation purely with aerial photogrammetry are overcome under the condition of assistance of less field work, aerial-photogrammetry-based existing line midline production is implemented in an office work and field integration mode, an aerial-photogrammetry-based existing line plane midline production flow is established, and the accuracy, format and standard of the method all meet the requirements of railway engineering.