On-line length measuring device for plate blank

The utility model discloses a plate blank on-line length measuring device, which is applied to continuous casting thick plate blank production equipment and relates to the field of plate blank production, the plate blank on-line length measuring device comprises a fixing assembly, a first detection assembly and a second detection assembly, the fixing assembly is arranged on one side of a plate blank conveying roller way, the fixing assembly comprises a guide rail, and the first detection assembly is arranged on the guide rail. The guide rail is parallel to the plate blank conveying direction; the first detection assembly and the second detection assembly are arranged at the two ends of the guide rail respectively, the first detection assembly and the second detection assembly can move along the guide rail, the first detection assembly comprises a first detector used for detecting the end of a plate blank, and the second detection assembly comprises a second detector used for detecting the end of the plate bla