The preparation of coal samples with full moisture content can be determined by the following methods based on their moisture content: 1. For coal samples with low moisture content, the coal samples should be directly crushed to a specified particle size of 6mm or less, slightly mixed and spread out, and then reduced to no less than 0.5kg using the nine point method. The coal samples should be immediately placed in a sealed container (with a sample volume not exceeding 3/4 of the container volume, the same below). 2. For coal samples with high moisture content, a crusher can be used to crush them at once to a particle size less than 13mm, and a coal sample of no less than 2kg can be separated and immediately placed in a sealed container. 3. For coal samples with high moisture content that cannot pass through the crusher smoothly, the oversized coal should be selected first and crushed to a particle size of about 13mm or less. After mixing, 2kg should be separated using the nine point method and immediately placed in a sealed container. Regardless of the type of coal sample, it should be prepared in a timely manner and the shrinkage operation should be rapid. Weigh the prepared full moisture coal sample, label it, and quickly send it to the laboratory along with the record. If the full moisture coal sample needs to be reduced, the coal sample can be slightly mixed and spread out, and then immediately reduced using the nine point method.