As the major loadbearing layer of the understructure of the nonballast track, the floor slab of the nonballast track system has high requirements in construction quality. Due to the narrow working space inside the tunnels, the rapid and highquality construction of the floor slabs inside tunnels becomes one of the most important aspects in the construction of passengerdedicated railway tunnels. The construction of the floor slabs of the nonballast track system inside Dabieshan tunnel is presented in the paper, which can provide reference for the construction of the floor slabs in other passengerdedicated railway tunnels.