Abstract: The effects of rolling process parameters such as laminar cooling mode, intermediate billet thickness, and coiling temperature on the mechanical properties of 16 mm thick 700L automotive beam steel coil and the first pass reduction of rough rolling on 14 mm thick 700L automotive beam steel coil, especially the low-temperature impact toughness at -20 ℃were studied. The results show that for 16 mm thick automotive beam steel coil, the comprehensive mechanical properties of the steel with dispersed laminar cooling mode during coiling are superior to those of the concentrated laminar cooling mode,insufficient compression ratio during the precision rolling stage leads to the appearance of coarse grain zone at 1/2 of the plate thickness. The experimental steel has low and unstable low-temperature impact absorption energy at -20 ℃.When the thickness of the intermediate billet increases from 48 mm to 57 mm, the low-temperature impact toughness of the test steel at -20 ℃ is stably controlled, the average impact absorption energy of the specimen is 199 J, and the mechanical properties such as strength, plasticity and toughness are reasonably matched; when the coiling temperature is 618 ℃, some grains at 1/2 thickness of the test steel plate become coarse and the precipitates precipitate along the grain boundary, resulting in a decrease in its low-temperature impact toughness stability at -20 ℃. When the first pass reduction of roughing increases from 26 mm to 33 mm, the average value of -20℃ low temperature impact work of 14 mm thick test steel increases from 122 J to 144 J, which is increased by 18%.