The essay aims to design a program by using software Matlab helping pick up doublet design in good quality, which can improve axis chromatic aberration、thrid order spherical aberration and thrid order coma. With using the program, a secondary spectrum is wirtten to sort axis chromatic aberration from high to low of glass combinations, and to find the two glasses whose V-number vale is high. The higher the V-number difference value is, the lower the power is, which helps reduce thrid order spherical aberration, thrid order coma and means the doublet in greatest value.