The influences of W doping at Mn site on the magnetic structure of the charge-ordering system La0.3Ca0.7MnO3 are studied by the measurements of M_T curves,M_H curves and ESR spectra of polycrystalline samples of La0.3Ca0.7Mn1-xWxO3(x=0.00,0.04,0.08,0.12,0.15) are studied. The results show that when the doping amount is 0.00≤x≤0.08, the charge-ordering(CO) phase exists in the system, the AFM/CO states coexist below the transition temperature, and the charge-ordering temperature Tco goes up with the increase of W doping content. For the sample of x=0.04, FM phase and AFM/CO phases coexist at low temperature, and FM is separated from PM both before and after the formation of CO phase; when x≥0.12, CO state melts, and the paramagnetism-ferromagnetism (PM-FM) transition exists at extremely low temperature.