The difficulties in the construction of the bottom of the dry dock of Honggu tunnel in Nanchang are presented. Countermeasures, including proper zone division of the dry dock bottom, zonal replacement filling, adopting angle steel for the sleeper beam, floating layers consisting of concrete and filtering channels and proper optimization of the drainage system, are adopted. In the end, the construction of the bottom of the dry dock has been completed successfully and relevant requirements have been complied with. 