Various approaches for generating wood grain patterns using computer graphics have been proposed so far. However, with such conventional methods, it is difficult to reproduce real wood grain patterns, as well as design wood grain patterns with impressions that reflect customer needs. This paper proposes a new approach for generating wood grain patterns. For instance, it can generate virtual trees by simulating tree growth taking into consideration environmental conditions, model fine tree tissues and reflection properties at the wood surface, etc. By applying these modeled factors, more diverse and accurate wood grain patterns can be generated. The authors also propose a method of controlling the grain patterns generated based on Kansei to realize grain patterns that meet customer needs. By building the basic system of the proposed method, various grain patterns could be generated, and grain pattern impressions controlled.