Abstract: In-situ remediation of soil and groundwater is mainly realized through vertical remediation wells technology, but this technology has a series of problems. The horizontal remediation wells(HRWs) technique is an innovative in-situ soil/groundwater remediation technology at contaminated sites, which can fully overcome the shortcomings of vertical wells. It can be used to target and clean up the contaminants precisely by means of horizontal directional drilling collaborated with conventional methods, such as chemical oxidation/reduction, soil vapor extraction, groundwater pump and treat, etc. It is mainly used at sites where conventional vertical drilling or trenching would be undesirable or impractical, and is especially suitable for contaminated soil and groundwater remediation beneath surface obstructions and active facilities. At present, the research and application of HRWs technology have not been conducted widely in China. The research advances of HRWs were introduced in the aspects of principles and characteristics, advantages and limitations as well as the history and development trend.This new technology was applied and tested at a petroleum hydrocarbon contaminated site in N City, J Province. The results show that the implementation of this technology is not limited by the active surface facilities with little disturbance to the surrounding environment. It has a greater contact area with contamination. The overall concentration of petroleum hydrocarbon in groundwater reached the remediation target value and was reduced by 96.47%. The successful demonstration of this technique can provide a practical reference and new vision for the development of in-situ remediation technology in China.