Participation of flexible loads in microgrid operation provides an effective approach for enhancing the efficiency of intermittent renewable energy utilization. The advanced automatic control level in an industrial microgrid makes it a good choice for dispatching generation and flexible loads cooperatively. This paper presents an economic operation model for industrial microgrids with multiple kinds of flexible loads, including industrial manufacturing loads, building thermal loads and electric vehicle (EV) charging loads. Detailed models of flexible loads are first formulated respectively and then integrated to an optimization model with an objective of minimizing the energy cost. A highly efficient solver GUROBI is next utilized in the MATLAB environment to solve the developed optimization model. Finally, a case study of a typical industrial microgrid is employed to demonstrate the essential features of the proposed model.