Grid environment is dynamic and open, therefore the reputation of entities in grid is becoming the focus of people's attention. Although, recently the study on the grid computing is resultful, the researches of reputation field are still not perfect, especially in the field of computational economy for grid. This paper presents a reputation calculation model, which is suitable in the environment of computational economy for grid. We also design a reputation control module (RCM) based on the reputation model, using for resource management in computational economy for grid. Additionally we give a detailed introduction of the internal structure and workflow of RCM. At last the paper shows the significance of our research through simulating experiments.