Abstract: With underground engineering excavated,geo-stress released and being regulated,surrounding rock quadratic stress field was formed.The distribution and magnitude of quadratic stress field relates to engineering geological condition and it affects safety construct and supporting measures directly.Quadratic stress field of surrounding rock was measured in site by using suitable for measuring and improved stress restoring method,combined numerical modeling,the variability features of surrounding rock quadratic stress field along the tunnel axis and cross-section were researched in this paper.The dependence between surrounding rocks quadratic stress and geo-stress field,surrounding rock class,fracture tectonic,epigenetic-surface formation,the state of underground water and construction,was analyzed.It has submitted data to research of quadratic stress field in underground engineering and information immediately to information construction in tunnel.