Abstract: With the improvement of computational ability and the demand for accuracy requirement of neutron kinetics, it has great value in engineering application to deal with the stiffness of three-dimensional space-time neutron diffusion kinetics better. Based on the stiffness confinement method (SCM) and the variational nodal method (VNM), a new combination of neutron kinetics model was developed. It is demonstrated by the numerical results that the SCM can handle the stiffness problem better with larger time step and higher computational efficiency, and be combined with the VNM.