“Enhancer trap” is an important technique to build and explore Drosophila brain gene expression pattern and its database. Large genome-wide screen for specific expression pattern in adult Drosophila brains by enhancer trap method provides fly tools for further understanding neural basis of learning and memory. Enhancer trap method was utilized to generate Drosophila P[Gal4] mutant library. Each mutant in library was crossed with GFP reporter flies (UAS-eGFP); heads of the adult off-springs were dissected to obtain the whole brain which were examined under the epifluorescence microscope and expression pattern of each mutant were further analyzed. JavaScript was utilized to establish an expression pattern library. A total of 2 677 mutant lines of Drosophila were obtained by P-element induced mutagenesis and subjected to expression pattern analysis. Most of mutated genes express in adult fly. 368 mutated genes specific express in the mushroom body, which was reported to involve in Drosophila olfactory learning and memory, and some others specific express in other neuron circuitries. Drosophila mutant libraries and genome-wide expression pattern database was built by enhancer trap method, which as a tool will be utilized to understand the function of genes and particular neural circuitries in Drosophila in the future.