The invention belongs to the technical field of metallurgical industry manufacturing and informationization of the metallurgical industry and relates to a segment-based multi-dimensional online quality evaluation system and method for steel coils. production process data and surface detection data for use in quality evaluation are acquired through a data interface; when a steel coil is off a line, the steel coil is divided into a plurality of segments along the length; the acquired data are read; according to business rules and product quality standards, process and surface defect quality results are separately judged; comprehensive level of each segment and quality level of the steel coil are finally acquired. Primary secondary process parameters and instrument defect information are acquired, and the production process data is maximally integrated; the business quality standards and control plan operation procedures are quantitatively and systematically processed, segment-based dimensional evaluation is performed at the moment when products are off the line, comprehensive inspection of the steel coil is achieved, labor for data collection is freed, quality inspectors can be helped to find quality problems in time so as to make following treatment, and product quality and enterprise economic benefit are finally improved.