A photogrammetry system, comprising: one or two photographing devices (21, 24), which are each disposed in a photographing direction substantially perpendicular to a direction of movement configured that an object to be measured moves in the direction of movement with respect to the photographing devices (21, 24), the photographing devices (21, 24) being able to photograph the object to be measured for at least two times at a predetermined time interval to obtain two images, respectively; and a data processing device; characterized in that: the data processing device calculates, according to a length of the object to be measured or at least one portion of the object to be measured in the images obtained by the photographing devices (21, 24), a transverse movement distance of the object to be measured or the at least one portion of the object to be measured in the two images and a speed of the object to be measured with respect to the photographing devices (21, 24), the actual length of the object to be measured or the at least one portion of the object to be measured; wherein the object to be measured moves at a speed V, and the photographing devices photograph the object to be measured for two times at a time interval t, or the object to be measured is stationary, and the photographing devices move at a speed V in a direction perpendicular to a photographing direction and photograph the object to be measured for two times at a time interval t; and the transverse movement distance of the object to be measured in the two images obtained by the two times of photographing is Dp, the length of the object to be measured or the at least one portion of the object to be measured in the images is Lp, and the actual length L of the object to be measured or the at least one portion of the object to be measured is obtained by the following formula: L = Lp × vt Dp one or two photographing devices (21, 24), which are each disposed in a photographing direction substantially perpendicular to a direction of movement configured that an object to be measured moves in the direction of movement with respect to the photographing devices (21, 24), the photographing devices (21, 24) being able to photograph the object to be measured for at least two times at a predetermined time interval to obtain two images, respectively; and a data processing device; characterized in that: the data processing device calculates, according to a length of the object to be measured or at least one portion of the object to be measured in the images obtained by the photographing devices (21, 24), a transverse movement distance of the object to be measured or the at least one portion of the object to be measured in the two images and a speed of the object to be measured with respect to the photographing devices (21, 24), the actual length of the object to be measured or the at least one portion of the object to be measured; wherein the object to be measured moves at a speed V, and the photographing devices photograph the object to be measured for two times at a time interval t, or the object to be measured is stationary, and the photographing devices move at a speed V in a direction perpendicular to a photographing direction and photograph the object to be measured for two times at a time interval t; and the transverse movement distance of the object to be measured in the two images obtained by the two times of photographing is Dp, the length of the object to be measured or the at least one portion of the object to be measured in the images is Lp, and the actual length L of the object to be measured or the at least one portion of the object to be measured is obtained by the following formula: L = Lp × vt Dp the data processing device calculates, according to a length of the object to be measured or at least one portion of the object to be measured in the images obtained by the photographing devices (21, 24), a transverse movement distance of the object to be measured or the at least one portion of the object to be measured in the two images and a speed of the object to be measured with respect to the photographing devices (21, 24), the actual length of the object to be measured or the at least one portion of the object to be measured; wherein the object to be measured moves at a speed V, and the photographing devices photograph the object to be measured for two times at a time interval t, or the object to be measured is stationary, and the photographing devices move at a speed V in a direction perpendicular to a photographing direction and photograph the object to be measured for two times at a time interval t; and the transverse movement distance of the object to be measured in the two images obtained by the two times of photographing is Dp, the length of the object to be measured or the at least one portion of the object to be measured in the images is Lp, and the actual length L of the object to be measured or the at least one portion of the object to be measured is obtained by the following formula: L = Lp × vt Dp