Abstract: Abstract:【Objective】 Knowledge of gene transcriptional regulation is a critical component of understanding many issues relevant to entomology, including pesticide and disease resistance, behavior, evolution, and development. Prothoracicotropic hormone (PTTH) is one of key player in regulation of insect development and growth. Properties of transcriptional regulatory of PTTH are assuming an increasingly important role in elucidating the molecular basis of developmental and tissue specific expression pattern in Bombyx mori. 【Method】In this paper, the promoter of PTTH gene was cloned and sequenced, then, the transcriptional regulatory elements in the promoter were predicted using Matinspector software. The nuclear proteins were extracted from the brains using high sucrose solution. Electrophoretic Mobility Shift Assay was used to analysis of the binding affinity of nuclear extraction to [α-32P]dATP labeled probe. 【Result】Some deduced cis-acting DNA elements were located in the promoter of PTTH gene of B.mori, including MEF2, TATA box, pbx-1, et al. The nuclear proteins were extracted from the brains, which can bind to the 119 bp DNA fragment near the transcriptional initiator of PTTH gene. When the 7 bp (TATATAA) of TATA Box was mutated （named MBS2）, the probe can not bind to the nuclear proteins. 【Conclusion】The nuclear proteins extracted were effective. It is demonstrated that the promoter can bind to the nuclear proteins of B. mori, firstly. The TATA Box in the promoter of PTTH gene was identified preliminarily.