The invention provides a no-plated-layer variable strength steel composite material. The composite material comprises a high-strength part and a low-strength part, and a transition area positioned between the high-strength part and the low-strength part; the high-strength part adopts all austenite area quenching and medium-temperature tempering; the medium-temperature tempering obtains a microscopic structure with a secondary hardening effect; and the low-strength part is renewedly heated and quenched after tempering of the high-strength part, that is, critical zone annealing and quenching of ferrite and austenite are performed to obtain double-phase steel of ferrite and austenite.