Abstract: The cellulose material formed by mixing general molecular weight pulp(DP=722) with a small quantity of super-high molecular weight pulp(DP≈10 000) was dissolved in N-methylmorpholine-N-oxide monohydrate(NMMO.H2O) and the resultant dope was spun by Lyocell process.It was found that the addition of super-high molecular weight cellulose did not enhance the strength and modulus of Lyocell fiber effectively.Combined with the analysis of the rheological properties of the dopes taken from different positions during spinning process,and the molecular weight and its distribution of cellulose in the dopes,it was clear that the addition of the super-high molecular weight cellulose resulted in dope separation when it flew through filter under the spinning pressure and therefore the mechanical properties of prepared Lyocell fiber could not be improved obviously.