The redesign of the daily necessities is an innovative reflection which can not only improve people’s living environment, optimize people’s life, but also cause people to renew their ideas. The successful cases of redesign of the daily necessities show that finding the truths from the ordinary everyday life in modern design and rejuvenating daily necessities can bring about extraordinary creativity. By taking reference from mathematical concepts and adopting combination laws such as the union, intersection, complementary sets and empty sets are the most common approaches to redesigning daily necessities. Looking for design in daily life is the necessary quality of the modern designer since people live in the ocean of design. Life itself is the origin of design while ultimately design is the reflection of life.