Imperfection or thick, thin and neps of yarn is a foremost problem of yarn manufacturing which create difficulties from fabric construction to end product development for customer and Imperfection of yarn has an adverse effect on fabric structure, uneven outcome during dyeing and printing as well as influencing handfeel and comfortness of end product. A standard production process of 35% Cotton and 65% Polyester Blended Yarn for 40Ne, 50Ne and 60Ne Ring Spun Yarn was maintained for a specific customer in a spinning mill and imperfections of 40Ne, 50Ne and 60Ne Ring Spun were measured by uster tester and thin (-50%), thick (+50%), neps (+200%) were tested and variation of 40Ne, 50Ne and 60Ne Ring Spun Yarn was observed to understand the variation of count versus yarn imperfection where finer yarn showed higher thin, thick and neps comparing to coarser yarn and a sequence of thin, thick and neps were resulted for three types of cotton and polyester blended yarn which can be distinguished as thin, thick and neps of 40Ne < thin, thick and neps of 50Ne < thin, thick and neps of 60Ne and such way imperfection index of yarn also showed higher for fine yarn comparing to coarser yarn which can be noted as imperfections of 60 Ne > imperfections of 50 Ne> imperfections of 40 Ne. So it can be decided that imperfection level of finer yarn is more significance in uster capacitance comparing to coarser yarn.