The study is devoted to the numerical simulation of droplet impact and rebound on a horizontal surface. The phase-field method (PFM) is used. It is firstly validated for several cases from literature concerning the spreading characteristics of the impact of a single droplet and the coalescence of two droplets. All the numerical results are in good match with experimental data from literature. The numerical method is then applied to study the impact behavior of a single AdBlue droplet under different conditions. Several drop-impact regime maps for physical parameters such as contact angle (90-170°), impact velocity U (0.01-10 m/s) and droplet diameter D (0.01-3 mm) are generated, in which the deposit and rebounce regime are identified. Then, a regime map based on dimensionless parameters Weber number We (0.05-4) and Reynolds number Re (100-800) is generated, showing good agreement with experimental data from literature. Furthermore, regime maps based on Weber number We and contact angle for droplets of different sizes are generated. The regime map for smaller droplet shows no good agreement with the model from literature. At last, th ... mehre effect of coalescence of two simultaneously impacting droplets on the rebound is investigated with this numerical method.