The invention relates to steel applied to automobiles, aiming at solving the deficiencies in the prior art that micro alloying elements are excessively added, the cost is high and the cost performance is low and other deficiencies. The measures are as follows: hot galvanizing bake-hardening steel with a yield strength of 180 Mpa is provided; the chemical components and the weight percentage of the chemical components are as follows: C: 0.001-0.008, Si: 0.045-0.055, Mn: 0.10-0.40, P: 0.01-0.03, Nb: 0.005-0.020, Ti: 0.0031-0.008, Als: 0.02-0.07, S: less than 0.015, N: 0.001-0.004, and the balance of Fe and unavoidable impurities; the preparation method has the following steps: rough rolling is carried out at the temperature of 1050-1100 DEG C, and finishing temperature of precision rolling is controlled within the range of 900-960 DEG C; rolling is carried out at the temperature of 700-760 DEG C, and cold rolling is carried out when the general reduction rate is between 65% to 85%; continuous annealing is carried out at the temperature ranging from 800 DEG C to 850 DEG C; cooling is carried out at the speed of 30-50 DEG C/ second; pinch pass rolling is carried out for standby. The steel applied to automobiles of the invention has the characteristic that after stamping moulding and baking varnishing treatment the steel is hardened; meanwhile, and depression resistance of auto parts is improved, thus facilitating automobiles to be safer and more energy-saving.