[en] Emergency Diesel Generator(EDG) which has similiar type and capacity in comparison with EDG in UCN 3,4 units will be adopted in Korean Next Generation Reactor (KNGR). But, difficulties in EDG operation and maintenance experiences in UCN 3,4 units have been presented. In this paper, concrete difficulties in the EDG maintenance of UCN 3,4 units were reviewed in view of operability and maintainability, and field opinions have been collected for improving the general arrangement(GA) design in KNGR EDG room. As a result of design improvement, horizontal laydown area was extended up to 50% compared with that of previous GA(rev. 0) on the base of required area for maintaining 2 sets of engine cylinder, and auxiliary pipe lines adjacent to the diesel engine, such as cooling, lubricating lines and so on, will be accommodated inside the trench between the wall and the engine body. The accessibility was improved by installing the checked plate on the top of this trench and securing the necessary space for maintenance