Recently, renewable power plants, utilize from clean and sustainable resources for electricity generation in the world. The ocean thermal energy conversion (OTEC) system uses from the ocean surface water as high temperature source and the water in the depth of the ocean as low temperature source. The difference between these temperatures is 20 0 C or more and a working fluid with low boiling point can be used for electricity generation. In a close cycle OTEC system, working fluid through a thermodynamic cycle based on the Rankine cycle can rotate the turbine and generate electricity. Due to the variation in the ocean surface temperature, the output power of the OTEC system changes and results in the numerous states in the generated power of this plant. Thus, in integrating the OTEC systems to the power system, many aspects of power system such as reliability may be affected and so new approaches must be developed for investigation these effects. In this paper, the reliability of the power system containing OTEC system based on the multistate reliability model and also based on the conditional value at risk concept is evaluated and the valuable indices used for generation expansion planning of the power system are calculated.