Recent day‘s improvement in the yarn quality is a main challenge in front of the textile technologist. Ring frame rubber cot shore hardness plays very important role in deciding the fibre control during drafting at ring frame and shore hardness is one of the main properties of top roller cot and varies for different types of fibre, application etc. in this paper the research study has been conducted on the medium grade cotton for 32s Ne yarn count and the effect of nine different spinning front line cots (Synthetic rubber cot) varying only in shore ‗A‘ hardness (63°,65°,68°,72°,75°,80°,83°,85°& 90°) on 100% cotton ring spun yarn has been investigated. The change in cotton yarn properties like, unevenness %, Imperfection levels (in all class), yarn strength, yarn hairiness, and yarn elongation with progressive change in shore ‗A ‗hardness has also been reported. The count and process parameter‘s from opening and cleaning machines that covers blow room & carding then breaker & finisher drawing, speed frame and up to ring spinning kept identical. As one progress from lesser shore hardness (63°) to higher shore hardness (90°) the yarn unevenness %, imperfection levels and hairiness gradually increases and also the yarn strength and elongation decreased. Finally From the results indicate that the yarn is with best evenness, imperfection, hairiness, tenacity and elongation results is obtained in case of using 63o shore hardness at the front top roller because lower the degree of shore hardness, higher the softness of rubber compound and vice versa even though softer cots under normal spinning conditions produces better yarns with better mass uniformity, IPI levels, hairiness, tenacity and elongation during the production of 32s yarn count on the other hand, the worst result has come when using shore hardness 90o at the front top rollers. Linear regression technique was used to analyse the data.