This paper describes the development of the interactive hullform transformation program. This program has many hull transformation functions such as main particular transformation, deadrise generation, section characteristic transformation, local transformation and CB, LCB variation, etc. MBASTRANS adopted the GUI(Graphical User Interface) using the OSF/Motif based on the X-Window system and used X-PLOT and GLBAX which are 2 and 3 dimensional graphic libraries, respectively. The interface module cans generate the information of the hullform for the SIKOB package and the hydrodynamic analysis.