The invention discloses a soft rock tunnel deformation control method based on anchor rod force analysis. A soft rock tunnel is excavated and subjected to deformation control construction from back to front according to multiple segments, and when any segment is excavated and subjected to deformation control construction, the method includes the steps that 1, surrounding rock basic mechanical parameters are determined; 2, the tunnel reserved excavated volume is determined; 3, the tunnel is excavated; 4, a tunnel preliminary bracing structure is determined; 5, tunnel deformation control construction is carried out, wherein in the tunnel preliminary bracing construction process, a flexible mold bracing structure is constructed from back to front; 6, a next segment is excavated and subjected to deformation control construction; 7, the step 6 is repeated multiple times till the full excavation and deformation control construction process of the soft rock tunnel is completed. The soft rock tunnel deformation control method is reasonable in design, convenient to achieve and good in use effect, the reserved excavated volume is determined according to the surrounding rock deformation condition of the soft rock tunnel, the flexible mold bracing structure is adopted for carrying out full-section bracing on the tunnel, the flexible mold bracing structure and the tunnel preliminary bracing structure are in coordination deformation, and deformation of the soft rock tunnel can be effectively controlled.