Abstract: With a view to determining a reasonable layout of compact spinning on FA506 ring spinning frame,a basic model of cross-section position of compact spinning was developed to analyze the influences of the spinning length of roller nip to thread guide,inclination of roller nip to thread guide,the length of compact field and the wrap arc of roller on the yarn breakage,the fiber band effect of compact spinning,transmission of twist and spinning tension & strength.The equation of reasonable cross-section technologic dimensions was derived.Furthermore,the range of reasonable cross-section technologic dimensions which have great value for reference was presented using MatLab.The results showed that reasonable inclination of roller nip to thread guide and the length of compact field is a pair of main contradiction which can be solved in harmony by optimizing the orientation and shape dimension of compact roller.