The invention provides a tunnel section rapid extraction method based on original point cloud data. The method comprises the following steps: step 1, scanning acquired tunnel surface original coordinate point cloud data Dr; step 2, calculating the slope k of the section S to be extracted, and obtaining sorted point cloud data Ds according to the value of k; step 3, roughly extracting the point cloud data to obtain point cloud data Dc; step 4, performing fine extraction on the point cloud data to obtain a point set Dp of the section; and step 5, converting the extracted section point set Dp into a plane coordinate system. According to the method, collecting a tunnel section design drawing and a horizontal curve element table and a vertical curve element table of an interval where a tunnel is located are collected, the center coordinate and the normal vector of the to-be-extracted section is calculated, two times of extractions, namely rough extraction and fine extraction, are performedand 90% of point cloud data can be filtered out in rough extraction, so that the calculation efficiency is improved, the extracted section coordinate data is finally obtained, and the extracted section coordinate data can be converted into a plane coordinate system according to needs.