In order to study the resistance characteristics of pile supported Ming dig tunnel excavation pile lateral soil, mechanical model and displacement modelare set up considering pile foundation pile lateral soil pressure insoil mass stress state. Secondly, according to the principle of function and displacement mode, the function and formula of velocity fieldfor pile supported Ming dig tunnel excavation pile lateral soil is established. Then, through the introduction of extreme limit method, the coefficient calculation methodis put forward considering the interface roughness coefficient of pile-soil pile horizontal bearing capacity of pile foundation pit supported Ming dig tunnel. At the same time, this method was applied to calculate examples. A comparative analysis between the theoretical calculation method and calculated results demonstrates the rationality and feasibility of this method. Finally, by using the method established in this paper, the influence of pile spacing, pile and soil contact surface coefficient and pile embedment depth of foundation pit on horizontal resistance coefficient is also analyzed. The results show that the horizontal bearing capacity of pile decreases with the decrease of the pile spacing and reaches to a minimum value. The level of the pile bearing capacity coefficient of Np pile soil increases with the increasing interface roughness coefficient alpha. When the pile-soil interface roughness coefficient alpha is unchanged，the horizontal bearing capacity coefficient of Np increases with the increase of buried depth. When the embedment depth ratio Z/D is larger than 7, the horizontal bearing capacity coefficient of Np increases with the increase of embedment depth and reaches a constant value.