A mutant strain P-15-1 was obtained from Aspergillus niger 3316 by treating with UV and N.M.. In comparation with the parent strain, its enzymatic activity was increased by 40%. The culture medium for producing pectinase consisted of 2%(NH4)2SO4, 2% wheat bran", 2% citrus peel power. The optimal culture conditions are as follows, initial pH4.0, temperature 30癈 and cultivation time 72h.An effective nutrient solution for biopulping has been selected. Papermul-berry was defiberated in 40h under the optimal culture condition, The pulps, handsheets and the waste liquor were analyzed and discussed.