The invention relates to a multicomponent alloy integrated spring flat steel which comprises the following chemical components in percentage by weight: 0.38-0.46% of C, 0.80-1.40% of Si, 1.00-1.70% of Mn, 0.50-0.90% of Cr, 0-0.15% of V, 0-0.050% of Nb, 0.0005-0.0025% of B, 0-0.030% of Ti, 0.0050-0.0300% of Al, at most 0.0050% of Ca, at most 0.020% of P, at most 0.010% of S, at most 0.0070% of N, at most 0.0020% of O, at most 0.0002% of H and balance of Fe. The invention adopts the compact technical production process comprising converting, refining, continuous casting, heating and rolling. Due to the microalloying of multicomponent alloy, including silicon, manganese, chrome, vanadium, niobium, boron, titanium, aluminum, calcium and the like, modification, and integration and optimization of molten steel purifying chemical technique manufacturing system, the flat steel product implements matching of high strength and favorable comprehensive properties, and has lower production cost.