Phytase gene of Aspergillus niger 963 was cloned into baculovirus transfer vector. DNA of the recombinant vector was co-transfected with Bm-BacPAK6 DNA into BmN cells, and recombinant virus was selected by plaque assays. The recombinant virus was identified by Dot blot and Southern-blot with the specific probe for phytase gene. Phytase gene was expressed in silkworm larvae and pupae. The expression product was 1.43 g/L haemolymph for silkworm larvae and 1.90 g/L haemolymph for pupae, respectively. The enzymic characteristicses of phytase expressed in baculovirus-expression system were studied in this paper.