This study was carried out to investigate the effect of biological treatment with Phanerochaete chrysosporium Burds fungi on the degradation process of chemical component of wood of Sengon (Paraserianthes falcataria (L) Nielsen) especially lignin, celullose and extractives and efficiency of the pulping process.The white-rot fungus, P. chrysosporium Burds was cultured at 28 ° C, RH 65 % for 7 days under growth medium, and inoculated to wood chips of Sengon and incubated for 4 weeks. The chips were then analyzed of its chemical components and then cooked by kraft process with 3 variation of active alkali (16%, 14%,12%) and 3 variation of cooking time (2; 1,5; and 1 hour).This study showed that fungal treatment could reduce the lignin content of wood chip from 26 % to 24 % and reduce the extractives content from 2,5 % to 1,7 %, and celullose content changed slightly. The highest screened yield (50,72 %) was reached on treated chips cooked with 16 % active alkali and 1,5 hours time cooking. The treated chips cooked with 14% active alkali and 1,5 hours cooking time has the same screened yield with untreated chips, 39,85% dan 39,32% respectively. The kappa number decreased from 7,97 to 2, 89. This means that bio-kraft pulping could reduce the active alkali requirement unto 12,5 % and reduce the cooking time unto 25 %.