The invention discloses a bus driving accident risk assessment system and a method thereof. The method comprises the following steps: establishing a bus driving accident risk assessment model by setting accident risk assessment indexes of a bus driver in the operation process, including behavior supervision, behavior identification and overspeed monitoring in different sections, substituting behavior supervision data, behavior identification data, vehicle displacement speed data, vehicle state data and the like generated by the bus driver in the operation process into the assessment model to obtain a bus driving accident risk assessment value, thereby predicting the driving accident risk of the bus driver and enabling a bus enterprise to carry out targeted safety education on bus drivers in advance.