Abstract: To accurately predict the evolution and distribution of temperatures around the heating boreholes is a crucial topic in the design of nuclear waste disposal. The main objective of this study is to investigate the steady-state temperature field for double boreholes problems, with the application in the design of the radioactive geological disposals. In the determination, the eccentric annular mapping theory and the Schwartz alternate method are employed to obtain the exact solutions of temperatures. Firstly, a novel Schwartz alternate method is developed to solve solutions of temperature in the multi-connected domain. Temperature field is then obtained by superimposing a series of single-borehole temperature solutions influenced by the negative "excess temperature" along the borehole boundary. Specifically, for the single borehole problem, a conformal transformation method is applied to accurately map the eccentric hole region in the physical plane to an axially symmetric annular region in the image plane. Meanwhile, combining the governing equations for the steady-state temperature in the image plane as well as the boundary conditions of "excess temperature", analytical solutions of temperatures for the whole domain are finally derived. Analytical solutions agree well with numerical predictions, verifying the efficiency of the developed analytical theory and model. Finally, parametric analyses are carried out to study the effect of the distance between twin tunnels and temperature boundaries at boreholes on the resulting temperatures.