Abstract: In order to ensure the reliability and security of working environments under the open network environment dynamically,a fine-grain real-time and dynamic trust monitoring model is proposed which is based on behavior attribute factor, penalty factor of bad frequency, penalty factor of reputation, penalty factor of hazard-warning frequency, union-recommendation trust, etc. Through monitoring the behavior change in the context of service nodes, the calculating method about the behavior risk value is discussed which is based on the degree of damage about bad behaviors. This can provide convenience for making new judgment.When work is completed, the updating method about trust encouragement or punishment is given. Experiment results show that the new real-time trust monitoring model is accurate and effective.