The invention relates to a 
helical weld 
pipe line outer 
diameter measuring device and a 
helical weld 
pipe line outer 
diameter measuring method based on view detection. The 
helical weld 
pipe line outer 
diameter measuring device comprises an industrial camera 1, an industrial camera 2, a grid calibration target, a linear 
laser generator, a 
cantilever, a guide track, a lifting mechanism and a measuring platform, wherein the plane of 
laser generated from the linear 
laser generator is perpendicular to the horizontal plane; the industrial camera is fixed on the guide track through the lifting mechanism; a central light axis is perpendicular to the plane of the laser; the industrial camera 2 is used for vertically taking images of the edge of a steel pipe and the 
laser light from top to bottom through the 
cantilever; the grid calibration target is arranged inside the plane of the laser and perpendicular to the central 
optical axis of the industrial camera 1; the calibration of the industrial camera is firstly completed; when a helical weld pipe is produced, 
laser light images are simultaneously taken by the industrial camera 1 and the industrial camera 2, and the outer diameter and the ellipticity of the helical weld pipe can be calculated by 
processing the images. Due to the cooperation of the double industrial cameras, the guide track and the lifting mechanism, dynamic measurement on the outer diameter and the ellipticity of helical weld pipes of different diameters can be achieved.