Studying the self-assembly behavior of DNA origami allows a better understanding of molecular assembly characteristics at the nanoscale. Presently, the mechanisms governing growth and dynamics of DNA origami assembly are still not very clear and there is a lack of direct visualization of the growth processes on the long single-strand scaffold. Here, we investigate the kinetics, especially the real-time seeding growth process of six special designs of 2D DNA origami at room temperature (RT) without the assistance of denaturing chemicals. The prealignment of single-strand long scaffold and logical seeding growth behaviors are revealed during the growth process at RT. Furthermore, we studied the thermal stability of the DNA nanostructures under limited structural defects. Revealed characteristics of seeding growth can be used to build large and complex DNA nanodevices capable of performing logical operations with nanometer precision.