Abstract: Based on the basic principle of sizing and through deduction,this paper has revealed,by a series of formulas,the internal correlation of key sizing factors such as sizing regain,weight added ratio after squeezing,moisture regain after squeezing,solid content,absorption ratio of warp after squeezing,moisture regain of raw warp.And their impact on high pressure sizing is studied.In addition,by means of these formulas,experiments of ″the process parameters in sizing″ by indirect test methods are implemented,which focus on guiding sizing production accurately and rapidly,as well as adjustment of technique.Moreover,this paper has testified reasonable section of the experienced formula set up by Mr J Trauter from Germany,focusing on relation among the key sizing factors such as absorption ratio of warp after squeezing,solid content,sizing regain,and some revision is made to it.