Generally,in the standard of determination of gallium in coal in our country,the method of Luo Danming B colorimetry assay was adopted, gallium chlorine acid Luo Danming B coloured complex was made from chloride gallium acid anions （GaCl4-） and Luo Danming B（ R ） in 6 mol/L hydrochloric acid.The existence form and the method for the determination of gallium described in coal were summarized， the experimental conditions were  researched, the main factors to influence the accuracy of the test results，ashing conditions, dissolved alkalinity and extraction time were investigated.