A novel unit commitment model to promote carbon reduction of a power system is proposed.Compared with traditional models，this one is improved in the following two aspects.On the one hand，low-carbon demand side resources，such as demand response，vehicle to grid and distributed renewable energy generation，are considered together with power supply resources to achieve an optimal schedule.On the other hand，a new fuzzy bi-objective optimization approach that can reflect the relevant priority between objectives is presented to strike an effective balance between economic objective and carbon emission objective.To solve the unit commitment optimization problem，the particle swarm optimization（PSO）is improved by employing crossover operator and mutation operator from the genetic algorithm，which enhances the global optimization ability of PSO.Numerical studies of a 10-unit system have verified the effectiveness of the model and the algorithm.