The production flowsheet of test steel SCM435 rod coil (/% ：0.33-0.38C

0.15-0.35Si

0.60-0.85Mn

≤0.025P

≤0.025S

0.90-1.20Cr

0.15-0.30Mo) is 80t BOF-LF-280 mm x325 mm casting bloom-160 mm x 160 mm hot-rolled billet-hot continuous rolling to Φ16 mm rod coil. The effect of 160 mm x 160 mm hot-rolled billet rolling to rod coil processes by normal rolling ( beginning rolling at 1060 °C

finishing rolling at 930-950℃

finishing exit temperature 860-900℃

cooling rate 0.5-0.6℃/s) and control-rolling-cooling (beginning rolling at 1060℃

finishing rolling at 820-850°C

finishing exit temperature 780-820℃

cooling rate 0.4-0.5°C/s) on structure and mechanical properties of steel SCM435 hot-rolled rod coil has been tested and studied. Results show that with decreasing the finishing temperature and cooling rate

the structure of steel hot-rolled rod coil is improved and the tensile strength of steel decreases obviously

that is the average tensile strength of steel SCM435 hot-rolled rod coil rolled by normal rolling process is 952 MPa with structure of ferrite + pearlite + bainite + martensite

while the average tensile strength of SCM435 hot-rolled rod coil rolled by control rolling-cooling process is 817 MPa with structure of ferrite + pearlite. Based on the principle of control-rolling-cooling the analysis on change of structure and properties of steel has been carried out.