Gene chip is a recently developed high-throughput gene expression analyzing technique. Key techniques and new development of gene chip are reviewed in this paper, including carrier(or substrate) surface chemical modification, preparations of DNA fragment, preparation of gene chips, tagging of the probes, hybridization, and analysis of gene chips. Comprehensive introduction of advantages and disadvantages of various technical taches and elements are introduced in this article. Particular attention is paid to further improvement needed to promote the popularization and application of this technology.