Abstract: Screening of actinomycetes strains AG7 with weathered coal the reaction to improve free humic acid content in weathered coal for preparing a humic acid fertilizer. With humic acid increase rate to determine the optimal culture conditions, including of cultivation temperature for 28℃ ,mixture of initial pH value for 6,the training speed for 160 r/min. Under the optimal culture conditions, different proportions of the weathered coal and bacterium fluid, preliminarily determine the proportion of improve humic acid 250g/500ml （weathered coal/bacteria liquid）. With preliminary got humic acid fertilizer and chemical weathering coal and humic acid fertilizer sold on the market, plant growth of contrast test was conducted, to research of its stimulation on plant growth, examine the different humic acid fertilizer on the sorghum seeds germination rate, plant height and fresh weight. Experimental results showed that humic acid bacterial fertilizer under the suitable concentration, on the sorghum seeds germination and growth had a certain role in promoting.