Varied types of Visual Display Unit (VDU) are used in modern process control rooms. The main purpose of present study is to identify and find solutions to usability problems of VDU user interface in process control room. The usability evaluation methods were heuristic evaluation, usability test, and SUMI questionnaire. Fifteen operators participated in the study. The main result from the usability test were that the time to solve the task depends on the number of false clicks and commands, and participants experienced that user interface doesn't support in an efficient manner, too many and difficult steps must be performed. To improve the user interface of VDU we have created number of guidelines; for example; create groups of the fields, buttons, text, place the buttons in functionally way, enable the user to open multiple windows, drag and drop is a dynamic operation.