Abstract: In order to study the density of potassium and Huaibei area of cotton yield and quality of 2006-2007, we made two years in a row of cotton cultivation test using the second saturated D-optimal design, to explore the density and fertilizer on cotton The production, and fiber length of the rupture of the value of the effect of the combined effect of the establishment of the equation.The results：The density of potash fertilizer and seed cotton lint production and both are related ，K and density of seed cotton and lint against each other is also a positive effect， Lint and seed cotton production are the highest range of facilities potassium 400.2 kg/hm2--409.0 kg/hm2, the scope of planting density is 36,136 / hm2 - 37973 strain / hm2; Cotton fiber length and fracture values reflect the effects of equation, potash fertilizer and density of the two types of quality indicators are positive effect, cashmere long the effect of potash fertilizer is greater than the density, fracture density effect is greater than the value of potash; fiber length highest Shi Potassium is the scope of 315.5 kg/hm2--367.7 kg/hm2, the density of 25,569 / hm2 - 26229 strain / hm2。