The invention discloses a compound production line system comprising a steel-pushing heating furnace, a stepping reheating furnace, a 3300mm four-roll reversing roughing mill and a steekle mill, wherein the steel-pushing heating furnace is used for heating a middle plate slab; the stepping reheating furnace is used for heating the plate slab used for rolling strip coils; the 3300mm four-roll reversing roughing mill is respectively connected with the steel-pushing heating furnace and the stepping reheating furnace for cogging the plate slab from the stepping reheating furnace to obtain a middle slab, and the middle slab from the steel-pushing heating furnace is subjected to reversible rolling after the middle slab is sent into the steekle mill; and the steekle mill is used for carrying outmulti-pass reversible rolling on the cogged middle plate slab. Compared with the prior art, the capacity is greatly increased.