Computer based control systems have been widely used in chemical processes with significant productivity improvement. However, the use of computer introduces benefits as well as hazards. A complete hazard analysis framework is proposed in this paper for this kind of processes. The framework involves representation of process, verification of control logic, identification of safety critical events, and application of a question library to the events. A novel modelling representation-Process Control Event Diagram (PCED) is developed and used to express the control logic and it＇s effect on the process. The behaviour of the process is obtained by simulating the propagation of the effects of control actions on the process through PCED. The question library is derived from industrial incident records. The whole procedure of applying the framework is illustrated by a case study.