Due to the influence of various factors, the census results inevitably deviate from the real total population. How to construct an estimation of the total population with good statistical properties and wide application scope and to accurately grasp the trend of population change is an important issue for the government's statistical work. In this paper, we explore the empirical method of the census annual population estimation of the UK Statistics Office, and propose a method of population estimation based on the combination of triple system estimation and ratio estimation. The simulation results show that the new method can better overcome the interaction bias caused by the independence of two systems, and improve the accuracy of the total population estimation based on the reasonable stratification of the population. At the same time, the research of this paper also puts forward the construction idea of ``the third set of demographic data resources'', which is not only the data foundation of constructing and applying triple system estimation, but also helpful to further promote the statistical modernization reform.