The study on interesting stochastic resonance of the Ising spin system (ISS), subject to a joint external field of weak sinusoidal modulation and stochastic white noise, was carried out through solving the meanfield equation of motion ba sed on Glauber dynamics, and some new features in the dynamic response and stochasti c resonance of the above ISS were also revealed. The periodic ally driven stochastic ISS shows the occurrence of characteristic nonequilibrium d y namic phase transition when the frequency and amplitude of driving field, the te mperature of system and noise intensity attain a specific accordance in quantity . Somewhat similar to the situation in sole sinusoidal field, our primary result indicates that the dynamic transition of ISS in an applying stochastic fieldre tains probably the feature of both discontinuous transition at low temperatures and continuous transition at high temperatures. The analysis was made concerning the nonequilibrium dynamic transition induced in the Ising spin system by exter nal stochastic force in detail.