The paper proposes an inseparability criterion for continuous variable systems based on the total variance of a pair of Einstein-Podolsky-Rosen (EPR) type operators. This criterion provides a sufficient condition for entanglement of any two-party continuous variable states. For Gaussian states, the criterion is shown to be both necessary and sufficient for inseparability. The authors derive a theorem that states for any separable quantum state, the total variance of a pair of EPR-like operators must satisfy a lower bound. For Gaussian states, this bound is violated if and only if the state is entangled. The paper also discusses the practical implications of this criterion, particularly in the context of quantum communication and computation, and provides an example to illustrate its application.The paper proposes an inseparability criterion for continuous variable systems based on the total variance of a pair of Einstein-Podolsky-Rosen (EPR) type operators. This criterion provides a sufficient condition for entanglement of any two-party continuous variable states. For Gaussian states, the criterion is shown to be both necessary and sufficient for inseparability. The authors derive a theorem that states for any separable quantum state, the total variance of a pair of EPR-like operators must satisfy a lower bound. For Gaussian states, this bound is violated if and only if the state is entangled. The paper also discusses the practical implications of this criterion, particularly in the context of quantum communication and computation, and provides an example to illustrate its application.