The invention relates to a waste plastic flotation device. The waste plastic flotation device comprises a crushing flotation machine, a first scraper conveyer, a secondary flotation machine, a second scraper conveyer, a tertiary flotation machine, an aerobiotic contact oxidation pond and a clean water basin pond. The crushing flotation machine is provided with an outer wall of the crushing flotation machine, a charge port of the crushing flotation machine, a crushing device, a screening device, a spraying device of the crushing flotation machine, a floating area of the crushing flotation machine, a charge area of the crushing flotation machine, an aeration area of the crushing flotation machine and a settling area of the crushing flotation machine. The secondary flotation machine is provided with an outer wall of the secondary flotation machine, a charge port of the secondary flotation machine and a spraying device of the secondary flotation machine. The tertiary flotation machine is provided with an outer wall of the tertiary flotation machine, a charge port of the tertiary flotation machine, a spraying device of the tertiary flotation machine, a floating area of the tertiary flotation machine, a charge area of the tertiary flotation machine, an aeration area of the tertiary flotation machine and a settling area of the tertiary flotation machine.