Droplet evaporation has received more attention for the applications including concentrating chemicals, coating, printing, spraying, drying, painting, biomedical sampling, etc. Deposition pattern form the evaporative colloidal droplet has many applications in the industrial applications. The process to form the configuration in the drying droplet has been investigated with simulation and experiments. Experimentally, the suspensions of colloidal droplet with the particle size at nano- and micro-scale nanoparticles in the deionized water were prepared. The suspensions are carried out by well stirring first and then putting in an ultrasonication bath to ensure the even initial dispersion of the particles in the water. The clean silicon wafer was used as a substrate for the colloidal sessile droplet drying. Right after the suspensions were prepared, we placed a tiny sessile droplet to dry in the open conditions. The drying patterns were directly recorded with the optical microscope. The formation of branched particle aggregation structures was observed during the droplet evaporation. The experiments demonstrated the dried patterns such as finger, coffee ring, uniform coverage and the combined structures. We have applied the kinetic Monte Carlo model and the diffusion-limited aggregation simulation to explain the self-assemble processes. A lattice-gas Kinetic Monte Carlo (KMC) is developed to explain the of the finger structure while the diffusion-limited aggregation simulation is development to explain the transition from the coffee ring to uniform coverage. The mathematical models control the variables which indicate the presence of liquid, particle or substrate in cells of the cubical lattice. The simulation domain mimics the shape of a sessile nanofluid droplet. The particle, liquid, vapor interaction, and the other factors are considered. The experiments can be reflected by the simulations.