A fluid dynamic rain-making apparatus includes a first tubular member (10) and a thermal conductor (20). The first tubular member (10) includes a fluid channel having a first opening (12) and a second opening (13). An axial cross section of the fluid channel (11) decreases from the first opening (12) toward the second opening (13). The thermal conductor (20) includes a second tubular member (21) attached to the second opening (13) of the first tubular member (10) and heat sinks (22) circumferentially arranged on an outer surface thereof. A fluid (A) enters the fluid channel (11) from the first opening (11) and forms a cooled fluid (A1) through flowing through the fluid channel (11) for cooling the second tubular member (21), thus the heat sinks (22) are cooler than the external fluid (A). Accordingly, moist air is cooled to reach the dew point to form water drop for rainfall.