Abstract: In order to improve the construction conditions of the chemical grouting in the underground mine, the paper had a study on each component affected to t he grout gel time of the modified urea formaldehyde resin grout for the surface pre-grouting and the grout performances.The results showed that the temperature would have high influences to the gel time, the volume error of the grout injected would have a min influence to the gel time and when the oxalic acid dosage was 0.3%0.6%, t he gel time of the grout could be easily adjusted and controlled.The modified urea formaldehyde resin grout would have a low viscosity, the gel time could be adjusted a nd controlled within 1060 min and the modified grout could be applied to the mine porous cracking strata and the surface pre-grouting.The modified grout of 120 m3 was injected into the porous igneous rock in the auxillary shaft of Zhaoguan Mine, Xinwen Mining Group.With the measurements during the mine shaft sinking, the water inr ush almost was zero and the grouting results were excellent.