Underground drill usage monitoring method

The present invention relates to a method of monitoring the condition of a downhole drill bit used, which belongs to the field of oil. Wherein the method comprises the following steps: Step 1: Determination of drill pipe torque Wi, where i is the ordinal number of the measurement, i = 1,2,3 ...; Step 2: Calculate the n consecutive current torque including torque includes the average torque step 3: standard deviation σa is calculated in step 2 of the n th torque; step 4: dispersion calculation step n-2 in the torque ka, according to a change condition used to monitor ka downhole drill bit. The method of the present invention can significantly improve the accuracy of monitoring, automatic monitoring, reduce labor intensity, and the method of the present invention is applicable to a wide range.