The innvention discloses a dehydrator capable of removing PM2.5 in coal gas. The dehydrator comprises a dehydration tank (11), a fog screen tank (12) and a sediment water bin (10), wherein an overflow hole is formed in the sediment water bin (10); the sediment water bin is connected with two sediment mud bins (37); hoses (17) are arranged in the sediment mud bins and connected with vapor-water pipes (15); mixed vapor-water in the vapor-water pipes is supplied to the hoses; the lower openings of the sediment mud bins are connected with mud valves (18) respectively; the sediment mud bins are connected with the dehydration tank (11) and the fog screen tank (12); the sediment water bin is provided with a water pump (13); a water outlet pipe (9) of the water pump is communicated to the upper part in the fog screen tank and communicated with a fog screen ring (4) to supply water; supplied water is supplied to a small nozzle (25) at the fog screen ring and then supplied to a spray nozzle (7); the spray central line of the spray nozzle is coaxial with a fog bin (6); and the spray nozzle is used for spraying a hollow conical flow beam (29).