Abstract: The concept of resource credit is introduced, and is used to describe the reliability and dynamic properties of resources. The key factors which influence resource credit are defined. The simple arithmetic to calculate resource credit is introduced. Through embedding the resource credit model into resource managing systems, the resource having the higher credit will receive tasks at a higher rate, and thus the grid system is more reliable. Experimental results show that the system which has embedded resource credit model can provide more stable services, meaning that the resource credit model is effective.