In Japan, the recycling rate of waste textiles, especially waste clothing, remains low. The more complex the textile structure, the more difficult it is to recycle by classification into raw materials. This study investigates the reduction of the final disposal volume of waste textiles based on colour. We valid colour combinations for recycling waste textiles when separated according to these criteria. Colours similar to principal hues from the Mansell Color System were used as the fundamental colour for specimens. We focused on hues in this study and prepared 45 specimens of shoddy, grain and yarn, respectively. They were obtained by mixing two coloured cotton according to the ratios of 25:75, 50:50, and 75:25 by weight. We prepared specimens that were then examined with sensory evaluation and colorimetry. The results were discussed in Chapter 2 for shoddy and Chapter 3 for powder and yarn. As a result, we were able to determine the colour combinations that had high and low favorable ratings. The findings indicated that an interior angle within 85°on the Munsell color circle was a key feature for high favorable rating. On the other hand, there is a possibility that the waste textiles can be recycled as fiber reinforcement for new plastic products with effective colour by separating into the group based on colour. Therefore, in Chapters 4 and 5, we discussed the effect of molding conditions such as content of fiber reinforcement and molding temperature on colour of molded products by extruding molding method. As a result, the lightness(L*) of the surface colour of products changed greatly according to the content of fiber. Also it is clear that the value of L* of products is approaching to the value of L* of fiber reinforcement with increasing of the content of fiber. In Chapter 6, the conclusion was described and it was concluded in this study that the separation of waste textile based on colour is effective for the recycling system which requires the favorable colour.