Increasing the comfortable sensation needs the work of all systems. After the aircraft has been completely made , making changes to enhance the comfortable sensation is quite difficult and the good result may not be got. So the aircraft designers have to consider the comfortable sensation at the beginning of designing aircraft. To solve the problem, this article uses a virtual reality system to design, assess and optimize the cabin comfortable sensation during the design stage. The system can help the designers to find out a suitable design scheme and save the design cost. This paper studies the thoughts and methods of designing a comfortable aircraft by Virtools.