The accuracy of coal sample analysis depends not only on analysis technology itself, but also on accurate preparation of coal sample before analysis. The coal sample preparation is a complex process including a series of links such as crushing, mixing, division and preservation. The optimization of this process plays a decisive role in improving and ensuring the accuracy of analysis results. In current coal sample preparation process, such factors as segregation of particle size, sample contamination, drying time and improper preservation conditions could affect the representativeness of sample and accuracy of analysis results. In this paper, the preparation method and process optimization of coal sample are discussed. The quality and efficiency of coal sample preparation are improved by optimizing such processes as crushing, mixing, division and preservation, which could lay the foundation for improving the accuracy of analysis result for coal sanple.