The invention discloses a heat treatment production technology of a low-alloy and high-strength bridge cable steel continuous casting billet. The low-alloy and high-strength bridge cable steel continuous casting billet comprises the following components in percent by weight: 0.90-1.20% of C, 0.90-1.10% of Si, 0.60-0.90% of Mn, smaller than or equal to 0.01% of P, smaller than or equal to 0.01% ofS, 0.20-0.40% of Cr, 0.60-0.80% of Nb and V, 0.010-0.015% of Ti, 0.005-0.015% of N and 0.0005-0.0015% of B. Titanium nitride particles separated out during solidification of the continuous casting billet and acicular ferrite are used as nucleating points of new austenite during austenitization based on electromagnetic induction coil heating, and the austenite is thinned under the austenite boundary pinning action of the particles, so that coarse columnar crystalline structures in the continuous casting billet are reduced or eliminated, thinned structures are provided for production in the later process, and the structures and the performance of a final product can be further improved.