Delayed rockburst occurred frequently in HangWen Railway's horizontal rock tunnel in Zhejiang Province, but there are few studies on its gestation mechanism and space-time tendentiousness. Therefore, taking the time-dependent deformation of tunnel surrounding rock induced delayed rockburst as the core, the characteristics and mechanism of delayed rockburst were studied and analyzed by means of in-situ stress test and statistical field rockburst data. The results show these as follows. Delayed rockburst has obvious time-space tendentiousness characteristics. Nearly 70% of the delayed rockburst occur in the excavation of 6 ~ 30 days in this area, and lag the palm faces of 30 ~ 100 m in space. The delayed rockburst mostly occurs in medium rockburst, and the rockburst grade and possibility show an inverted "V" trend with time and space. Hard rock has obvious ductility and time-dependent deformation characteristics in high in-situ stress environment. Under unloading conditions, the stress releasing rate is the most important factor inducing delayed rockburst. After a certain distance of excavation, strain energy mutations occur at different locations around the tunnel, and a high strain energy density is maintained, which is prone to high-level rock burst. The above results provide a basis for predicting delayed rockburst and applying corresponding supporting measures in the future.