Abstract: According to the disadvantages of long time and slow speed of measuring the ash content of coal by slow-ashing method,based on analyzing the influence of change of testing condition on ash measurement accuracy,provides a new plan from aspects of control of the ashing time and coal sample quality; also analyzed the new ash curve samples,and finds the reasonable interval to improve the ash condition whose accuracy has been proved. As a result,the ash value from new plan conforms to the arbitration law and this is a scientific and practicability plan,and the testing time shortened effectively.