The invention belongs to the field of domestic drinking water deep treatment, and relates to a deep treatment device and method of domestic drinking water. The device comprises a process water pipeline for leading in process water, an ozone adding point, primary/secondary compound filter material filters, a sealed telescopic water storage container and an independent circulating pump. The method includes the steps of introducing ozone into input process water, subjecting the primary compound filter material and the input process water with the introduced ozone to contact reaction for primary coexistence of simultaneous oxidization, catalysis and adsorption to obtain primary output process water, introducing ozone into the primary output process water, subjecting the secondary compound filter material and the output process water with the introduced ozone to contact reaction for secondary coexistence of simultaneous oxidization, catalysis and adsorption to obtain secondary output process water, adding ozone to the secondary output process water which enters the sealed telescopic water storage container, and setting the independent circulating process so that it can be ensured that the primary deep treatment process and the secondary deep treatment process are reliably operated. The problems of active carbon replacement, biological leakage, water resource waste, health disadvantage and the like in domestic drinking water deep treatment in the prior art can be solved.