Abstract: The production process flowsheet of steel 45CrAlMo (/% : 0. 40 - 0.50C, ≤ 0.60Mn, 0.15 - 0.45Si, 1.30 ~ 1. 70Cr, 0.15 ~ 0. 30Mo, 0. 85 ~ 1.20Al) is 60 t EAF-LF-VD-argon shielding casting 2. 1 t ingot-forged to 120 mm x 120 mm products. The eSect of parameters of deoxidation in EAF steelmaking and LF refining process, VD degassing and continuous casting process on oxygen content and Al₂O₃ inclusions in steel has been analyzed. With the process measures including decreasing S content in liquid at end LF from original <0, 015% to 0. 008% , modifying feeding aluminium wire to adding aluminium ingot, decreasing VD vacuum from 100 Pa to 67 Pa, modifying adding CaSi to non calcium treatment and decreasing casting temperature of liquid from original 1 585 ~ 1 595℃ to 1 570 - 1 580 °C , the macro inclusions are eliminated, the B series and D series inclusions in steel decrease respectively from rating 1. 5 to rating 0. 5, the ratio of nondestructive-testing qualified steel increases from 67% to 98% and the yield of products increases from 55% to 68%.