The invention relates to a seamless tunnel structure adopting ECC concrete post-cast strips and a construction method of the seamless tunnel structure, and belongs to the technical field of tunnel construction. Tunnel secondary linings are constructed in a segmented mode, and one post-cast strip is reserved between every two segments of secondary linings. The temperature stress and concrete shrinkage stress of secondary lining concrete cast in advance are reduced through the post-cast strips, reinforcing bars are reduced in the post-cast strips, deformation is induced to be generated on the post-cast strips, ECC concrete is used for casting the post-cast strips, concrete cracks generated by differential settlement and loads are reduced through the ultrahigh toughness and self-healing capacity of the ECC concrete, and the super-long seamless tunnel structure is achieved. The ECC concrete is adopted for casting the post-cast strips, the width of the concrete can be effectively controlled, cracks generate din the tunnel operation process are avoided, and then the cracking and water leakage problem of a tunnel is fundamentally solved.