The invention provides a pipeline inner wall three-dimensional reconstruction algorithm based on a monocular image sequence, and the algorithm comprises the steps: determining pipeline center coordinates through a monocular image on the basis of the monocular image sequence, determining a straight line on the basis, and merging the straight line into a two-dimensional image to obtain a pipeline inner wall image. On the basis of the pipeline inner wall images, the elevation of the pipeline inner wall is calculated through the difference between the two pipeline inner wall images according to the triangulation principle, and three-dimensional reconstruction of the pipeline inner wall is achieved. The method has the advantages of being high in adaptability, easy to implement and high in reconstruction speed.