Peking Univ, Dept Tech Phys, Beijing 100871, Peoples R China
; Peking Univ, MOE Key Lab Heavy Ion Phys, Beijing 100871, Peoples R China
; Chinese Acad Sci, Inst High Energy Phys, Beijing 10039, Peoples R China
; Lab Nazl Sud, I-95123 Catania, Italy
A density-dependent relativistic mean field (DRMF) theory is extended to that at finite temperature and density, and the liquid-gas phase transition of warm nuclear matter is investigated. Our results are compared with those obtained from the Walecka's mean field theory. The critical values of temperature, density, and pressure are calculated by the DRMF. The obtained critical temperature is T-c=12.66 MeV by using the parameter set A, which is in accord with recent experimental observation.