Abstract: This paper studied and analyzed the stability of seamless turnout. Starting from the mechanical characteristics of each element member of the track structure division, the paper established the three-dimensional space finite element calculation model by MATLAB programming, analyzed the stability of the jointless turnout online, obtained the change trend of the turnout displacement by the model calculation given the temperature rise conditions, found the position of the peak point, obtained the change of displacement with temperature by changing the range of temperature rise, and obtained the allowable range of temperature rise. The results show that the most disadvantageous position points appear at the tip of the rail, the tip of the rail, the heel of the center rail and the separation of the straight side strand of the seamless turnout. The analysis of the causes of the peak points shows that the connection forms of the components as an important part of the rigidity of the track frame and the medium of the temperature force transmission directly affect the stability of the turnout. The displacement is linear with temperature. With the increase of temperature, the displacement value increases gradually. Based on this, a reasonable design basis for locking rail temperature can be provided. Finally, the paper put forward corresponding maintenance suggestions according to the position of peak point.