In weft knitting jacquard system, much variety patterns with several colors can be designed. But many of patterns may have poor grace and beauty. So choice of interesting and stylish patterns from wide set of patterns is difficult. Genetic algorithm that is an optimization system based on artificial intelligence can be used to solve the problem. Genetic algorithm is a method to respond to problems that are indissoluble by common methods and must using try and fault test to solve them. If there are many responses, it is too difficult to survey all of them. Genetic algorithm can include a wide range of responses and find best of them by receiving feedbacks from the problem. Interactive genetic algorithm is a type of genetic algorithm that receives necessary feedbacks from user. User is determinant of best of responses. So interactive genetic algorithm can be used in design optimization and choosing ideal patterns. In this research, interactive genetic algorithm is used to plan software of optimization of pattern in weft knitted fabric. Results show that the software is capable to determine interesting and stylish patterns and can detect ideal patterns for user. The softwares user interface can receive data and feedbacks from user and adapt itself with different qualification and styles. Patterns and colors produced by the software tend to interesting and stylish types during newer generations and user can aim the software to produce ideal patterns and colors. Because of more variety about colors, changes in fitness of them are wider and so it is necessary to produce more generations in this phase of optimization.