With the improvement of living conditions, interior design (hereinafter referred to as ITD) has become an indispensable basic matter in people’s life, which can meet the purpose of improving people’s living needs. Through ITD, we can gradually move towards intelligent life and other aspects. Traditional ITD is based on hand-painted renderings, which has been difficult to meet the demands of the development of the information age. Therefore, designers are looking for new ways of ITD, which can better achieve the effect of ITD. The expression of ITD is mainly divided into four links, including plan practice, sketch design, effect drawing expression and construction, namely plan, sketch, effect drawing and construction drawing. With the rapid development of computer, designers have gradually used software rendering, which can let customers know the effect. First of all, this paper analyzes the expression of ITD. Then, this paper analyzes the expression methods based on the computer renderings. Finally, some suggestions are put forward.