Bayesian Network (BN) is a graphical network model for the description of the variables between causal uncertainties. It is built for uncertainty modeling and reasoning, processing related to forecasting, intelligent reasoning, diagnosis, decision making, and risk/reliability analysis. Firstly, a brief presentation on BN was given. Then the development and function expansion of BN within the recent 30 years was outlined, and BN application in the field of engineering technology including fault diagnosis, reliability analysis etc. was reviewed. Finally BN existing deficiencies and future research trends was summarized and discussed.