This paper illustrates a nodal probabilistic production cost simulation at the load point of a composite power system for assessing operating cost in long term expansion planning of power system. This new nodal production cost simulation model includes capacities and uncertainties of generators as well as transmission lines. This simulation methodology comes from the nodal composite power system equivalent load duration curve (CMELDC) based on the new effective load model at load points. The nodal CMELDC can be obtained from convolution integral processing of the outage capacity probabilistic distribution function of the fictitious generator and the original load duration curve given at the load point. It is expected in future that the new simulation model based on the nodal CMELDC proposed in this study will provide some solutions to many problems based on nodal and decentralized operation and control of an electric power systems under competition environment. The nodal CMELDC based on the new model at load points can extend the application areas of nodal probabilistic production cost simulation, probabilistic congestion cost assessment, analytical method approached outage cost assessment and nodal reliability evaluation etc. at load points in future. The characteristics and effectiveness of this new simulation model are illustrated by a case study of a test system