Abstract: In order to understand the active regularity of low molecular weight organic acids on coal gangue nutrient，different kinds and different concentrations of low molecular weight organic acid (malic acid，citric acid，oxalic acid) are added to the unweathered coal gangue，to analyze the changes and differences of pH，available nitrogen，available phosphorus and available potassium after 7 d，30 d，60 d.The result shows：compared with the control,adding citric acid and malic acid can reduce pH value of coal gangue，while adding oxalic acid can enhance the pH value of coal gangue；malic acid and citric acid have a certain release effect on the available nitrogen of coal gangue，but oxalic acid has inhibitory effect；After the treatment of malic acid and citric acid，the content of available K of gangue decreased，oxalic acid was opposite.In the aspect of available phosphorus，organic acids all increased the content of available phosphorus in coal gangue.With the increase of the concentration of low molecular weight organic acids and the prolongation of culture time，the pH value of the coal gangue treated with citric acid and malic acid basically decreased，while oxalic acid was opposite.With the increase of experimental period，the content of available nitrogen and available phosphorus of coal gangue showed an upward trend，but only the available potassium showed a downward trend.Along with the increasing concentration of low molecular weight organic acids，application of citric acid and malic acid makes the available nitrogen content of coal gangue is basically a downward trend.Adding citric acid and malic acid makes the available nitrogen content of coal gangue is basically in decline，oxalic acid showed an opposite trend.Coal gangue available potassium and available phosphorus content of organic acid concentration increased with no obvious regularity，it shows a little effect of fixation and release of organic acid concentration on coal gangue available potassium and phosphorus fractions.

Key words: Low molecular weight organic acids, Coal gangue, Available nutrient, Ecological restoration