A rainwater catchment, purification, and desalination treatment apparatus, comprising a rainwater catchment apparatus (1), a first filtration apparatus (2), a sterilization apparatus (3), a second filtration apparatus (4), a sedimentation apparatus (5), a third filtration apparatus (6), a fourth filtration apparatus (7), a heating apparatus (8), and a liquefaction apparatus (9). The rain water catchment apparatus (1) comprises a catchment frame (11), a first concentrating ring (12), a first protruding ring (13), a catchment plate (14), a first fixed block (15), a first push rod (16), a first cylinder (17), a first support plate (18), a first dispersion funnel (19), and a first conduit (10). The first filtration apparatus (2) comprises a first filtration frame (21), a first filter (22), a first supporting ring (23), a second filter (24), a first blocking ring (25), a first horizontal rod (26), and a first vertical rod (27). The sterilization apparatus (3) comprises a first catchment funnel (31), a second connecting rod (32), a first baffle (33), a first movable bracket (35), a second cylinder (34), a sterilization frame (36), a first heat dissipating frame (37), a first heating rod (38), and a first oblique plate (39). The second filtration apparatus (4) comprises a second filtration frame (41), a first connecting block (42), and a second conduit (43). Employment of the described apparatus allows the catchment of a sufficient amount of rainwater at times of increased and reduced rainfall, thus satisfying demand.